protobuf: Add support for deprecated groups

[Jozott00]

Subsystem
Protobuf

Problem Description
Groups were not supported or implemented, and they even caused a crash when the wire contained a GROUP tag.

Solution
The PR implements group support, which resulted in 10 more tests passing the conformance tests, specifically proto3 tests that validate the correct parsing error behavior for invalid END_GROUP tests.

However, functionality is also implemented for proto2 and editions that actually use groups in their proto file.

=== Conformance Test Results ===
Total baseline tests:   5545
[+] Passed tests:       1392
[-] Failed tests:       4153

[Mr3zee]

@Jozott00 looks like auto-lint on commit was applied to some generated classes

[Mr3zee]

⚡️⚡️⚡️

Do we enable proto2 tests and editions then?

[Jozott00]

Proto2, Proto2 Editions and Editions2023 conformance tests are activated in the next PR.
At the stage of this PR there are a couple of issues with the proto2 generated source code that leads to compile issues which are not related to groups.