Fix LU parser rules to support all comments in a file

[sw-joelmut]

minor

Description

This PR updated the LU lexer and parser rules to support the case with a LU file with only comments in it.

Specific Changes

• Updated LUFileParser.g4 and LuFileLexer.g4 files.
• Autogenerated the ANTLR files after updating the rules.
• Updated expected results in unit tests to match the changes.
• Added a new unit test to cover the new scenario.

Testing

This image shows the unit tests passing after the changes.

[coveralls]

Pull Request Test Coverage Report for Build 384362

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage remained the same at 78.379%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetNextViableTime.cs	1	93.94%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetPreviousViableTime.cs	1	93.94%
<!--	Total:	2		-->

Totals
Change from base Build 384324:	0.0%
Covered Lines:	26174
Relevant Lines:	33394

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💛 - Coveralls