Adding 26.0.0 tag

Last commit DSL unparsing is supported

Adding 25.0.0 tag

Adding 24.0.0 tag

V622-017: Fix env grouping with non-default metadata.

The routine for grouping lexical envs would previously always flatten grouped
envs. However, this process would discard the `default_md` field of the nested
grouped envs.
The implementation now decides to flatten grouped envs only if the resulting
env behavior is the same.

RA22-015: Add test for calls to non callable entities

New script to create a source package for Langkit_Support

TN: TA19-011