Add option for symbol matching logic.

[iteratee]

The no_symbol_match makes command line completion a lot less useful. It disables any matches for file names with symbols in them. This prevents completing things like ":b foo/bar" to ":b foo/bar.txt" or ":b foo_" to ":b baz/foo_bar.txt". Add an option disallow_symbol_nonprefix_matching that prevents a match if it contains a symbol and isn't a prefix match. Make that option the default. Add the option to documentation and tests. Add to the examples for command line setup disabling the option.

[joshbode]

@iteratee I was just about to make a similar PR - thank you! This has been bothering me for a while :)

My other thought was to use the keyword_pattern per source in place of char.is_symbol, which for cmp-cmdline would include all non-blank characters: https://github.com/hrsh7th/nvim-cmp/compare/main...joshbode:nvim-cmp:joshbode/keyword-symbol-check although, it's less direct than your solution.

[hrsh7th]

LGTM. Thank you. Sorry. I produced conflicts unexpectedly. Could you solve it?

[iteratee]

Sorry for the delay. Rebased.

[hrsh7th]

Thank you.