Release 6.0.0-pre.20220201.3 (2022-02-11)

Baseline: c7652d87

Cherry picks:

   + 1c0cf8ee:
     Undelete BigIntegerCodec deleted in
     https://github.com/bazelbuild/bazel/commit/16753d6ab16c22ed8cfd42
     47e05c695223b67616. Belatedly realized needed for Starlark
     bigint serialization.
   + 382b187d:
     Automated rollback of commit
     9998c636.
   + 45ce5459:
     Rollback
     https://github.com/bazelbuild/bazel/commit/8174262bf946e31df86476
     014c6f231f46ca0882

This release contains contributions from many people at Google, as well as Denys Kurylenko, Keith Smiley.