[WIP] POC for reading multi-line JSON in string columns

[shrshi]

Description

Addresses #15277
Given a JSON lines buffer with records separated by a delimiter defined at runtime, the idea is as follows -

1. Modify the JSON tokenization FST to consider the passed delimiter to generate EOL token instead of the newline character currently hard-coded.
2. Modify the whitespace normalization FST to strip out unquoted \n and \r. Invoke the FST as a pre-processing step.

Note that this is not a multi-object JSON reader since we are not using the offsets data in the string column, and hence there is no resetting of the start state at every row offset.

Current status:

• Example FST that implements runtime configurable transition characters
• Adding transitions to handle unquoted newlines and carriage returns in whitespace normalization FST

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.