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/docs/implementing_proto3_presence.md b/docs/implementing_proto3_presence.md
index 7c3e213..4abfbd5 100644
--- a/docs/implementing_proto3_presence.md
+++ b/docs/implementing_proto3_presence.md
@@ -131,11 +131,11 @@
 
 ```
 # One option:
-$ ./src/protoc test.proto --cpp_out=. --experimental_allow_proto3_optional
+$ protoc test.proto --cpp_out=. --experimental_allow_proto3_optional
 
 # Another option:
 $ cp test.proto test_proto3_optional.proto
-$ ./src/protoc test_proto3_optional.proto --cpp_out=.
+$ protoc test_proto3_optional.proto --cpp_out=.
 $
 ```
 
@@ -152,7 +152,7 @@
 run into a different error:
 
 ```
-$ ./src/protoc test_proto3_optional.proto --my_codegen_out=.
+$ protoc test_proto3_optional.proto --my_codegen_out=.
 test_proto3_optional.proto: is a proto3 file that contains optional fields, but
 code generator --my_codegen_out hasn't been updated to support optional fields in
 proto3. Please ask the owner of this code generator to support proto3 optional.
@@ -201,7 +201,7 @@
 generator to generate a file containing proto3 optional fields:
 
 ```
-$ ./src/protoc test_proto3_optional.proto --my_codegen_out=.
+$ protoc test_proto3_optional.proto --my_codegen_out=.
 ```
 
 ### Updating Your Code Generator