Drop plan parser dependency on antlr4

[ericvergnaud]

Our current PlanParser enforces use of ANTLR4 to parse input.
This dependency is undesirable, and does not provide any benefit.

Thanks to #1200, this is no longer required.

This PR:
Removes dependency on antlr4 in PlanParser

Requires #1200

Progresses #869

Supersedes #1192

[github-actions]

Coverage tests results

448 tests  ±0   414 ✅ ±0   4s ⏱️ ±0s
  6 suites ±0    34 💤 ±0 
  6 files   ±0     0 ❌ ±0 

Results for commit e857f0d. ± Comparison against base commit c8b5af8.

♻️ This comment has been updated with latest results.

[jimidle]

Making this less generic will force reimplementation of code in the specific plan parsers. I don't think that this is a good idea. Dependency on ANTLR is not really a problem for the parser I think.

Perhaps you can explain why you want to dothis?

[ericvergnaud]

Making this less generic will force reimplementation of code in the specific plan parsers. I don't think that this is a good idea. Dependency on ANTLR is not really a problem for the parser I think.

Perhaps you can explain why you want to do this?

I agree it's not a big problem (yet) however:

• dropping it is not a big problem either
• I foresee various situations where we want to parse a plan using an existing parser that is not ANTLR based.