Fix: bmqp protocol Wconv warns

[melvinhe]

*Issue number of the reported bug or feature request: #87 *

Describe your changes
This PR attempts to fix all current -Wconversion warnings caused by faulty error checks, data type inconsistencies, and potential overflow/truncation data loss in ‘bmqp_protocol.cpp‘ as well as associated header and test files.

It should also clear out over a dozen errors that lead to at least 100 ‘-Wconversion‘ warnings in the BlazingMQ build logs such as, but limited to, the following:

In file included from /home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.t.cpp:30:
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.t.cpp: In function ‘void test1_breathingTest()’:
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.t.cpp:720:31: warning: conversion from ‘int’ to ‘unsigned char’ may change value [-Wconversion]
  720 |                       sh.flags(),
      |                       ~~~~~~~~^~
/home/runner/work/blazingmq/blazingmq/src/groups/mwc/mwctst/mwctst_testhelper.h:360:34: note: in definition of macro ‘ASSERT_EQ’
  360 |         _assertCompareEquals("", X, Y, #X, #Y, __FILE__, __LINE__);           \
      |                                  ^
      
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.h: In member function ‘BloombergLP::bmqp::MessagePropertiesInfo::SchemaIdType BloombergLP::bmqp::MessagePropertiesInfo::schemaId() const’:
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.h:3518:27: warning: conversion from ‘unsigned int’ to ‘BloombergLP::bmqp::MessagePropertiesInfo::SchemaIdType’ {aka ‘short unsigned int’} may change value [-Wconversion]
 3518 |     return d_schemaWireId >> 1;
      |            ~~~~~~~~~~~~~~~^~~~
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.h: In constructor ‘BloombergLP::bmqp::RdaInfo::RdaInfo(unsigned int)’:
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.h:3568:17: warning: conversion from ‘unsigned int’ to ‘unsigned char’ may change value [-Wconversion]
 3568 |     d_counter = internalRepresentation;
      |                 ^~~~~~~~~~~~~~~~~~~~~~
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.h: In member function ‘BloombergLP::bmqp::RdaInfo& BloombergLP::bmqp::RdaInfo::setCounter(unsigned int)’:
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.h:3603:19: warning: conversion from ‘unsigned int’ to ‘unsigned char’ may change value [-Wconversion]
 3603 |         d_counter += counter;
      |         ~~~~~~~~~~^~~~~~~~~~

/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.cpp:836:50: warning: conversion from ‘BloombergLP::bslstl::StringRefImp<char>::size_type’ {aka ‘long unsigned int’} to ‘int’ may change value [-Wconversion]
  836 |                                        str.length())) {                       \
      |                                        ~~~~~~~~~~^~
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.cpp:844:5: note: in expansion of macro ‘CHECKVALUE’
  844 |     CHECKVALUE(UNUSED4)
      |     ^~~~~~~~~~
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.cpp: In static member function ‘static int BloombergLP::bmqp::StorageHeaderFlagUtil::fromString(std::ostream&, unsigned char*, const string&)’:
/home/runner/work/blazingmq/blazingmq/src/groups/bmq/bmqp/bmqp_protocol.cpp:912:18: warning: conversion from ‘int’ to ‘unsigned char’ may change value [-Wconversion]
  912 |             *out |= value;
      |             ~~~~~^~~~~~~~

Testing performed
Ran through the CI's unit, formatting, and integration tests.

Additional context

Mainly casting to fix data type inconsistencies in my first diffs for this PR to start with a solution that is least invasive. Several cases may need additions like a precondition check, adjusting function signature, or changing a data type, although most changes seem to be fine after further review. I also left a few individual comments on noteworthy diffs.

[melvinhe]

@pniedzielski A lot of other functions and dependencies reference these 'bmqp_protocol' files. So these changes, after running these adjustments through the CI, surprisingly reduced over 8,000 occurrences of '-Wconversion' (from 12,238 down to 3,848)!

[678098]

Nice catch @melvinhe!

[melvinhe]

@pniedzielski @678098 The changes in this commit seem to be fine and ready to merge soon, but feel free to take a look or sanity check. Most of these edits just deal with relatively simple data types, so the changes shouldn't really change core code functionality (other than removing a boat-load of build logs). Besides 'Tests / IT [multi/fsm_mode]' which seem to be due to recent ubuntu changes rather than this PR, the CI checks seem to pass.

[pniedzielski]

@melvinhe Some of these are a touch more involved, so I will look at it again tomorrow morning, but it looks good to me! Probably will be able to merge tomorrow.

[pniedzielski]

Thank you!

[pniedzielski]

Sorry see above changes.

[melvinhe]

@pniedzielski confirming that CI checks passed after removing the nested cast. We're now down to 1,625 and 2,513 in docker & ubuntu builds respectively (from tens of thousands originally)!

[melvinhe]

Sorry see above changes.

Changes Resolved