Data analysts should be able to Text.match, Text.match_all, Text.is_match to find or check matches

[radeusgd]

Pull Request Description

Implements https://www.pivotaltracker.com/story/show/181266092

Important Notes

Also renaming Text.location_of and Text.location_of_all to Text.locate and Text.locate_all.

Checklist

Please include the following checklist in your PR:

• The documentation has been updated if necessary.
• All code conforms to the
  Scala,
  Java,
  and
  Rust
  style guides.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed: Enso GUI was tested when built using BOTH
    ./run ide build and ./run ide watch.

[jdunkerley]

Still not quite sure on the name for locate / locate_all but otherwise looks good and if we come up with a better name can rename.