Fixes issue = #9079
Label = feature

This PR adds a scalar function to perform REGEXP REPLACE in Pinot. The semantics of using this scalar function is as follows:

• If matches is not found, inputStr is returned as such.
• By default, all occurrences of the matched patterns are replaced unless the occurence parameter is not -1.
• Default match flag is case sensitive. Can be overriden with the flag parameter

Parameters:

1. inputStr (required): Input string against which regexp match and replace should be performed.
2. matchStr (required): String or regexp to match against inputStr
3. replaceStr (required): String or regexp to replace if a pattern is found.
4. startPos (optional): Starting index from where matching should be performed. Default value is 0.
5. occurrence (optional): The occurrence of the matched pattern must be replaced. Default is -1 where all found patterns will be replaced.
6. flag (optional): Single character flag that controls how the regex finds matches in inputStr. Default flag of empty is case sensitive match. If an incorrect flag is specified, the function applies default case sensitive match. Only one flag can be specified. Supported flags are:

• i -> Case insensitive
• m -> Treats the string to match as multiple lines
• x -> Add comments to the regular expression

We can support more flags in the future.