Add Configuration Key lombok.builder.toBuilder (Fixes #3758)

[Mahmoud-Khawaja]

Description

This PR introduces the lombok.builder.toBuilder configuration key, allowing toBuilder() to be enabled globally for all @Builder annotations via lombok.config. If not explicitly set in the annotation, the configuration value is applied (default: false).

Changes

• Added BUILDER_TO_BUILDER key in ConfigurationKeys.java.
• Integrated config key handling in HandleBuilder.java.
• Ensured explicit annotation settings override configuration values.

This provides more flexibility in testing and code generation.
Fixes #3758.

[rzwitserloot]

I'm not entirely sure lombok.config is the right place for this sort of thing. Config is always fighting with itself: On one hand, lombok never was intended to be silent magic - the source file on its own without knowing what lombok.config contains ought to be enough to at least guesstimate what's happening.

Then again, your class still has @Builder on it; it should therefore be somewhat obvious where toBuilder() is coming from.

I'll discuss this one with @rspilker before merging.

One consideration fighting against this, @Mahmoud-Khawaja, is OpenJDK's plans for with. It might be limited to records (all the more reason to use toBuilder() more!), but it would look something like:

LocalDate x = fetchSomeLocalDate();
LocalDate y = x with {
  year = 10;
  month = 12;
};

If that was part of OpenJDK, it reduces the boilerplate considerations (the 'bang' part of the 'bang for the buck' equation that lombok features have to balance out).

[rzwitserloot]

Talked it over with @rspilker ; we're going to accept this.

[rzwitserloot]

Reviewed the code:

• The merge conflict is trivial; master now has a new config key added at the end. The order between yours and the new one is not important.
• Your one commit contains the update, but no docs (that's allright, we can write them), no tests (acceptable, we'll write them), and a whole boatload of weird docker stuff. That has to go.
• Please add your name to the AUTHORS file for legal reasons.

If you could add the name to this PR we can accept it. And we'd take it as a kindness if you rebase it, remove the docker stuff.

[Mahmoud-Khawaja]

done, thanks!