Remove reflection from XP Core

[thekid]

This pull request implements xp-framework/rfc#338 and removes reflection from XP Core.

Continuous disintegration

• Access members (properties, methods, constants) via lang.XPClass
• Member encapsulations in lang.reflect
• Proxy and InvocationHandler classes from lang.reflect
• Annotation API in lang.XPClass
• Class details API for members
• Dependency of lang.FunctionType on class details API
• Remove class parser

Size

Before:

$ du -ksh src/*/php
831K    src/main/php
1019K   src/test/php

After:

$ du -ksh src/*/php
774K    src/main/php
915K    src/test/php

[thekid]

Generics use annotations, which means we have the following options:

1. Drop generics support (see also Extract reflection to its own library rfc#338 (comment))
2. Rewrite generics support to use PHP 8 attributes via reflection, and drop PHP 7 support (see also Drop PHP 7 support rfc#343)
3. Same as 2) - but create a simple annotation parser for PHP 7 which is loaded only on demand.
4. It might be possible to fold class parser and generics creation into a single-step process

[thekid]

Dependency of lang.FunctionType on class details API

For this to work, we need to be able to parse API doc types in FunctionType::verify(). This has the following 2 prerequisites:

• Type::named() is more liberal about trailing comments, so we're able to parse @return self This instance. See handling in lang.reflect.ClassParser::typeIn()
• We are somehow able to parse use statements to be able to resolve imports correctly. We already need this for running scripts, see xp.runtime.Code, the code there could be integrated with a slight refactoring.