feat(#13): add :Freeze ... complete behaviour

[AlejandroSuero]

As mention, this will allow to have completion to tweak freeze options/flags from the vim cmdline:

Usage:

• :Freeze your completion trigger (usually <Tab>) and select one.
  • Once selected, append = and the desired value, eg. :Freeze language=txt will translate to --language=txt.

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Demo with complete options (only language implemented):

complete-behaviour-demo.mp4

Note

I showcase also the problem mentioned that vim.bo.ft won't always work or cases where freeze has no filetype support.

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TODO:

• Parse options like boolean and table so it can be validated.
• Validate options once the arguments are passed.
• Implement all the options.

[isabelroses]

Amazing work. Thank you very much.