Remove all autotools usage (#10132)

* Bazelfying conformance tests

Adding infrastructure to "Bazelify" languages other than Java and C++

* Delete benchmarks for languages supported by other repositories

* Bazelfying benchmark tests

* Bazelfying python

Use upb's system python rule instead of branching tensorflow

* Bazelfying Ruby

* Bazelfying C#

* Bazelfying Objective-c

* Bazelfying Kokoro mac builds

* Bazelfying Kokoro linux builds

* Deleting all deprecated files from autotools cleanup

This boils down to Makefile.am and tests.sh and all of their remaining references

* Cleanup after PR reorganizing

- Enable 32 bit tests
- Move conformance tests back
- Use select statements to select alternate runtimes
- Add internal prefixes to proto library macros

* Updating READMEs to use bazel instead of autotools.

* Bazelfying Kokoro release builds

* First round of review fixes

* Second round of review fixes

* Third round of review fixes

* Filtering out conformance tests from Bazel on Windows (b/241484899)

* Add version metadata that was previously scraped from configure.ac

* fixing typo from previous fix

* Adding ruby version tests

* Bumping pinned upb version, and adding tests to python CI
diff --git a/examples/WORKSPACE b/examples/WORKSPACE
index 3897572..e9811ef 100644
--- a/examples/WORKSPACE
+++ b/examples/WORKSPACE
@@ -10,9 +10,11 @@
 #
 # http_archive(
 #     name = "com_google_protobuf",
-#     strip_prefix = "protobuf-main",
-#     urls = ["https://github.com/protocolbuffers/protobuf/archive/main.zip"],
+#     sha256 = "c29d8b4b79389463c546f98b15aa4391d4ed7ec459340c47bffe15db63eb9126",
+#     strip_prefix = "protobuf-3.21.3",
+#     urls = ["https://github.com/protocolbuffers/protobuf/archive/v3.21.3.tar.gz"],
 # )
+
 local_repository(
     name = "com_google_protobuf",
     path = "..",