Add heirline component

[Davidyz]

Closes #225 .

The heirline component is accessible via the following snippet:

require("vectorcode.integrations").heirline({ 
  show_job_count = true,
  component_opts = {
    -- put other field of the components here.
    -- they'll be merged into the final component.
  },
})

[Davidyz]

@Yorizel I reused the lualine component and made this very basic component. It works when I put it in statusline, but not for tabline. I'll see if I can fix this.

Also, I plan to put some other options (like hl) into the opts parameter for the function that builds the component. Is there anything specific that you'd like to see from it?

EDIT: The tabline thing was a config problem on my side. It's working for tabline too.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.75%. Comparing base (03a7020) to head (8ceff82).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #226   +/-   ##
=======================================
  Coverage   99.75%   99.75%           
=======================================
  Files          21       21           
  Lines        1627     1627           
=======================================
  Hits         1623     1623           
  Misses          4        4           

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[Yorizel]

Nothing specific tbh, just the Abílio to integrate with my current heirline is awesome