code duplication inside Program.g4

[yegor256]

This block contains duplicated code: https://github.com/cqfn/eo/blob/master/eo-parser/src/main/antlr4/org/eolang/parser/Program.g4#L131-L180 Would be great to get rid of duplication. I made it like this, after the discussion: https://stackoverflow.com/questions/64635366/how-to-make-antlr-consume-all-available-elements-using-recursion

[yegor256]

@andreoss can you help here? budget=1h

[andreoss]

@yegor256 Taken.

[yegor256]

@andreoss it's done, I believe?

[andreoss]

@yegor256 The structural duplication between application and htail remains, but many improvements had been done.
In #570, #611, #567, #563, which are PRs for this issue.

So this issue can be closed and replaced with a new one

[Graur]

@andreoss Did you finish this issue?

[yegor256]

@andreoss @Graur I'm closing. I will submit new issues, if see more problems