Overloaded internal return codes in TBL service

[skliper]

Is your feature request related to a problem? Please describe.
Multiple return codes are defined as -1, this defeats the purpose of named codes and doesn't allow for unique handling, checking the error code is also not actually testing that the expected incorrect code was returned.

cFE/modules/tbl/fsw/src/cfe_tbl_internal.h

Line 50 in 84ba9a9

#define CFE_TBL_NOT_FOUND (-1)

cFE/modules/tbl/fsw/src/cfe_tbl_task.h

Lines 59 to 78 in 84ba9a9

	/** \brief Value indicating when no load is in progress */
	/**
	** This macro is used to indicate no Load is in Progress by assigning it to
	** #CFE_TBL_RegistryRec_t::LoadInProgress
	*/
	#define CFE_TBL_NO_LOAD_IN_PROGRESS (-1)
	/** \brief Value indicating when no Validation is Pending */
	/**
	** This macro is used to indicate no Validation is Pending by assigning it to
	** #CFE_TBL_RegistryRec_t::ValidateActiveIndex or #CFE_TBL_RegistryRec_t::ValidateInactiveIndex
	*/
	#define CFE_TBL_NO_VALIDATION_PENDING (-1)
	/** \brief Value indicating when no Dump is Pending on a Dump-Only Table */
	/**
	** This macro is used to indicate no Dump is Pending by assigning it to
	** #CFE_TBL_RegistryRec_t::DumpControlIndex
	*/
	#define CFE_TBL_NO_DUMP_PENDING (-1)

Note there's at least one cases where an index is initialized to one of these error codes, which is especially fragile (#1519)

Describe the solution you'd like
Defined unique error codes, if they every get passed out an API really they should be defined in cfe_error.h

Describe alternatives you've considered
None

Additional context
Code review

Requester Info
Jacob Hageman - NASA/GSFC