Add missing setters to `Rfc5424LayoutBuilder` (#4076)

* Restore support for documented `Rfc5424Layout` attributes

In `2.21.0`, `Rfc5424Layout` was migrated from a factory method to the builder pattern. During this change, the recognized names of several configuration attributes unintentionally diverged from the documented ones.

As a result, some documented attributes were no longer recognized, while new, undocumented names were introduced.

This change restores support for the documented attribute names while continuing to accept the names introduced in `2.21.0` for backward compatibility.

Fixes #4022

Co-authored-by: Volkan Yazıcı <volkan@yazi.ci>

* Add missing setters to `Rfc5424LayoutBuilder`

This change introduces setter methods for the private fields added to `Rfc5424LayoutBuilder` in version `2.25.4`.

These fields were originally introduced to restore configuration options that existed in `2.20.0` but were unintentionally renamed in `2.21.0`. Due to semantic versioning constraints, setters were not added at that time.

With the `2.26.0` release, it is now appropriate to expose these fields via setters, restoring full configurability and improving API usability.

* fix: wrong reference in Javadoc

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Co-authored-by: Volkan Yazıcı <volkan@yazi.ci>