[BUG] Data Prepper strings do not support $

Describe the bug

Strings in Data Prepper do not allow a $ character. This can be problematic for any situation, but especially when using a regex pattern to get the end of a line.

To Reproduce

Create a pipeline with a route like:

/some_field =~ "^prefix-[a-zA-Z0-9-]+$"

Run Data Prepper.

You will get some cryptic errors.

Caused by: org.opensearch.dataprepper.expression.ExceptionOverview: Multiple exceptions (37)
|-- org.antlr.v4.runtime.LexerNoViableAltException: null
    at org.antlr.v4.runtime.atn.LexerATNSimulator.failOrAccept(LexerATNSimulator.java:309)
|-- org.antlr.v4.runtime.InputMismatchException: null
    at org.antlr.v4.runtime.DefaultErrorStrategy.sync(DefaultErrorStrategy.java:270)

Change the regex by removing the $. The route works as expected.

Expected behavior

I should be able to run Data Prepper with $ in the strings.

Start by reproducing the Data Prepper pipeline route shown in the issue and trace the route expression parsing that produces the lexer errors. Confirm the affected expression-string handling, then verify that the same regex containing $ runs successfully without errors.