Prepare 2.12.0.dev0.

[benjyw]

[ci skip-rust]

[benjyw]

Internal

---

• Have dependabot add a label to PRs (#14910)

• [internal] small codegen backend cleanups (#14899)

• [internal] BSP: update compile rules to work again (#14906)

• [internal] inject ScalaPB runtime dependency (#14898)

• Adding DigestTrie/Snapshot diffing (#14872)

• [internal] BSP: cleanup target resolve and source roots computation (#14871)

• Upgrade Pex to 2.1.73. (#14875)

• [internal] BSP: stub out remaining scala RPCs (#14870)

• [internal] delete non-experimental java protobuf backend (#14866)

• [internal] restore experimental codegen backends disabled for 2.10 release (#14407)

• [internal] BSP: get third-party deps working for Scala (#14860)

• [internal] Rename build wheels steps to include architecture (#14861)

• gitignore Pyenv's .python-version file. (#14862)

• Ensure in CI that every PR has a category label. (#14855)

• [internal] Second round of softwrapping user-visible strings (#14851)

• [internal] Softwrapping global options (#14853)

• Remove redundancy in how we apply DEFAULTs in config. (#14852)

• [internal] Use static workunit names, and lazily construct metadata based on the level (#14854)

• [internal] softwrap the codegen subdir (#14796)

• [internal] Simplify config parsing. (#14846)

• [internal] BSP: switch to aggregate build targets (#14835)

[benjyw]

I punted on the deprecations, pushing them to dev1, because I don't have the knowledge or bandwidth to deal with them.