Add support for using keyboard layout in Language widget

[Osyx]

Implements a layout_name variable accessible via {lang[layout_name]} in the Language widget.

Closes #90.

This config:

widgets:
  language:
    type: 'yasb.language.LanguageWidget'
    options:
      label: "<span>\uf11c</span>{lang[language_code]}-{lang[country_code]}  {lang[layout_name]}"

will give this:

[Osyx]

It seems to work somewhat, but when I'm running it locally it only updates the layout on start, and then never updates it again, even though the rest of the returned object is updated.

Open to suggestions on how to fix! Haven't really written python in ages, and never used Win APIs really, so I'm very rusty.

[amnweb]

Open to suggestions on how to fix! Haven't really written python in ages, and never used Win APIs really, so I'm very rusty.

Welcome to the Windows API jungle xD

[amnweb]

I have tried to play with that but I have no idea why layout_name is not updating, maybe it is that API limitation or something else not sure :(

[Osyx]

@amnweb Hmm that's sad, idk how we should go forward then, I didn't manage to find another way either :/

I saw in the docs that they recommended using Windows.Globalization.Language.CurrentInputMethodLanguageTag instead. Tried implementing that, but it yielded the same result as GetKeyboardLayout(thread_id), though it also only updated on startup. Also saw this comment:

This property returns a value for the currently active input method on the thread with keyboard input focus. Calling this on a background thread may not return the expected results.

which is basically the only way to use CurrentInputMethodLanguageTag it seems, so that seems like a dead end.

We could rename it to initial_layout_name but might not be worth due to people expecting more of it.
I think my use case is quite uncommon as well. So maybe we should just close this PR, idk.

[Osyx]

It should now work as expected!

Showcase:
test-yasb-layout.webm