Add table->regex convenience functions
Add table->regex convenience functions

These functions can be used in testing/development to generate a
regular expression character class which covers the desired
`included_obfuscations`. In addition to a general purpose
formatting function, `table_as_regex()`, functions are provided
which are specific to the format needed for each of
* MS searches (database regex engine), `table_as_ms_search_regex()`
* MS Regexp (Ruby Regexp) ,`table_as_ms_regexp_regex`
* and SD regexes (Python, using the `regex` package),
`table_as_sd_regex()`.

Charcoal-SE/SmokeDetector,Charcoal-SE/SmokeDetector