Consolidate actions into a single builder binary (#1947)
This change consolidates most actions into a single binary `@go_sdk//:builder`, which is a private dependency of the toolchain instead of an implicit dependency of rules. The public API has not changed. This has several benefits:
* Better abstraction in the toolchain; alternative toolchains can use their own builders.
* Fewer binaries need to be built and sent to the remote cache.
* Actions can share code easily, which will enable further consolidation of actions.
The following actions were converted:
* GoStdLib
* GoAsm
* GoCover
* GoPack
* GoCompile
* CGoCodeGen and CGoImportGen
* GoLink
* GoTestGenTest
* GoGenNogo
Fixes #1891
34 files changed
