Proposal: Remove absolute paths from error messages (ideally before 6.0)

[IllusionMH]

Absolute paths block micration to TSLint test format, since error message will depend on file location, and can't be universal across Windows/Linux/Mac OS.
File name/path should be in formatter output (I've checked all core formatters and they provide absolute path).

There are 3 rules that use absolute path in its erros:

• export-name source - use file base name - will be easy to compare.
• missing-jsdoc source (already deprecated in this repo) - remove absolute path and change : to . at the end of error message.
• react-no-dangerous-html - source - remove absolute path and of source file string before it.

What do you think? How critical to have absolute path here (especially last one)?

As for me - it will make error messages hard to read, because path can be too long.
In IDE I'm already in that file and in CI formatter will output path relative to

[JoshuaKGoldberg]

Agreed that it'd be good to remove these even without the conversion to the new test format and that it'd be good to do this pre-6.0. Let's get this in on 11/5 so we can release 6.0 on 11/5.