Fix indirect left recursive rule operator precedence via delegated operator precedence

[MisterErwin]

Resolves #4460

Operator precedence is currently (incorrectly) reset to zero, when a left-recursive rule contains other (non-left)recursive elements.

grammar T
e : m | e '*' e * ID;
m: '-' e;
ID : 'a'..'z'+ ;

The ATN for rule e is shown below:

In case no indirect recursion was present (e : '-' e; | e '*' e * ID;), the ATN would look like the following:

Notably, without indirectness, <e[2]> signals a precedence used.

For completeness, the ATN of rule m is shown below too:

The <e[0]> (or in Java: e(0);) in rule m resets the operator precedence to zero, which is not correct (see issue #4460 or the tests added by this PR).

Proposed solution:

In case we detect a rule reference resulting in a binary or prefix recursion, we introduce an optional parameter int _dp (similar to the p parameter of left recursive rules) with a default of 0 to the targeted rule.
(This would replace the old <e[0]> by a <e[_dp]>.)

This PR does not touch the ATN behavior of ANTLR (well.. almost not. The possible precedence value _dp is now excluded during the ATN creation, but where this value is now set, any precedence was 0 before - yay).

This MR also introduces tests for additional attributes for rules (but not for left recursive ones, because ANTLR outputs an error message for these: rule e is left recursive but doesn't conform to a pattern ANTLR can handle)

The precedence option for indirect left-recursive rules is now set to "_dp", which is a new parameter introduced (similar to the existing _p).

Breaking changes:

This PR would prevent optional parameters from being added to parsers for the Dart target via the grammar.
Normal parameters are not affected, thus I would argue that change to be not of importance.

The reason I found this bug at all was that with large grammars,
I wanted to use the same rules (such as formulas) in multiple other rules.

The expected token position of the TestSymbolIssues#testUndefinedLabel test had to be modified by 5 tokens ((= dp 1)).

Thanks to Ken (@kaby76) for the initial directions over on SO

(By accident this also fixes #4477 :) )

P.S.: I've run a bunch of tests on internal grammars generated using the changes proposed, which so far has not shown additional errors.

P.P.S.: I am not sure if a RuleWalker similar to the LeftRecursiveRuleWalker instead of my LeftRecursiveRuleTransformer#isBinaryOrPrefix method would have been the better option - (but my version is at least easier to step through while debugging)

P.P.P.S.: The DOTGenerator is not aware of the presence of the _dp value for rererences - if desired, I can add this functionality (but wanted to refrain from doing so before the other changes were discussed.)