Remove the `@internal` annotation from the attribute reader

[mbabker]

Gedmo\Mapping\Driver\AttributeReader isn't really internal. If you're running an application that doesn't actually use annotations (but the annotations library still gets installed because of dependencies like this one where there's still a hard coupling), the only way to actually configure this library to not use annotations is to use this @internal annotated class. Which is also typehinted in a fairly decent number of public APIs. So, let's just remove the annotation.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (1ec37fb) 79.26% compared to head (8bf69fb) 79.33%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2743 +/- ## ========================================== + Coverage 79.26% 79.33% +0.06% ========================================== Files 162 162 Lines 8513 8506 -7 ========================================== Hits 6748 6748 + Misses 1765 1758 -7 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[franmomu]

Agree about making it non-internal, but I would like to take a look at some of the methods. IIRC the ones in plural are not really used, I think I can take a look at those this week.

[franmomu]

thanks @mbabker! It wasn't easy to remove, so when the times comes we can deprecate those methods.