Adds a new CoderTranslator for Java SchemaCoders.

[acrites]

The new translator splits out the Schema proto from the toRowFn and fromRowFn's so that runners can check the Schema proto for compatibility updates such as reordering fields. Previously, the coder was simply translated as a custom java coder, which runners couldn't reason about.

Since this is a potentially backwards incompatible change, this new coder format is guarded by the UpdateCompatibilityVersion StreamingOption being 2.76 (or earlier).

This fixes a few issues related to Schemas and pipeline updates: addresses #36496, #30276, #29245.

This PR is essentially a roll forward of the rollback #38514 with the breaking behavior in python fixed. I ran :runners:portability:java:ulrLoopbackValidatesRunner locally with these changes and the tests now all pass.

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[acrites]

@kennknowles and @scwhittle

[github-actions]

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[acrites]

assign set of reviewers

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[Abacn]

Since we have pipeline options now, we can check runner capability to translate to use SchemaCoder only when runner supported it. Then we don't need to worry about breaking changes on different runners for now.

[kennknowles]

I don't think we want to start translating to a different portable pipeline for different runners, though... seems like the issue in #33859 (comment) should just be fixed.

[acrites]

I've found that if I add Schemas to the list of coders to be ignored here it causes the previously failing post-commit (beam_PostCommit_Java_ValidatesRunner_ULR) to pass. This makes it so that Python treats the new schema urn as unknown and just passes it along as bytes.

With that change, should I go back to the previous implementation where we use the new schema coder type unless specifying compatibility 2.76 or earlier? i.e. start using this new coder type with 2.77 and later.

[github-actions]

Reminder, please take a look at this pr: @ahmedabu98

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R: @chamikaramj for label java.

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[acrites]

I believe I've fixed the Python runner issues that previously caused this PR to get rolled back. I ran :runners:portability:java:ulrLoopbackValidatesRunner locally and it now passes.

[Abacn]

Thanks, this LGTM as

• the previous version of the PR was approved

• Internal import (958568454) shows presubmit tests (on local Dataflow runner) previously failing now passing

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.17%. Comparing base (a26ecfd) to head (d18c7b8).
⚠️ Report is 14 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #39594 +/- ##
============================================
+ Coverage 57.09% 57.17% +0.07% 
Complexity 3639 3639 ============================================
Files 1191 1194 +3 Lines 192556 193273 +717 Branches 3816 3814 -2 ============================================
+ Hits 109946 110495 +549 - Misses 79042 79212 +170 + Partials 3568 3566 -2 

Flag	Coverage Δ
python	79.82% <100.00%> (-0.03%)	⬇️

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