[BEAM-7274] Add DynamicMessage Schema support

[alexvanboxel]

Add DynamicMessage schema support. This is different from
generated classes as it uses the proto descriptors. It uses
the ProtoDomain as an index for searching embedded messages.

R: @reuvenlax

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Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---		---	---
Java
Python		---			---	---
XLang	---	---	---		---	---	---

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website
Non-portable
Portable	---		---	---

See .test-infra/jenkins/README for trigger phrase, status and link of all Jenkins jobs.

[alexvanboxel]

Run Java PreCommit

[alexvanboxel]

R: @reuvenlax this is an implementation for DynamicMessages. It takes into account the new Logical Types and also use RowWithStorage instead of going with the getters.

[alexvanboxel]

@reuvenlax this is ready for review. It has feature parity with the static compiled proto, including all logical types.

[alexvanboxel]

Run Java PreCommit

[alexvanboxel]

This branch has been updated to take the new Logical Types into account.

[alexvanboxel]

Run Java PreCommit

[alexvanboxel]

@reuvenlax@iemejia@TheNeuralBit I've tested this PR extensively on Dataflow. This is way more stable than the original DynamicMessage schema implementation.

Can I get a LGTM, that I can focus on the options. Thanks.

(master is failing, it was green till rebase)

[alexvanboxel]

Run Java PreCommit

[alexvanboxel]

Run Java PreCommit

[reuvenlax]

A few comments.

[reuvenlax]

One small comment, but otherwise LGTM for merge.

[reuvenlax]

I don't see this function being used anywhere. Remove?

[alexvanboxel]

I used it in a production pipeline, but as it's not available in the other providers I removed it, (squashed and rebased).