Port extension to GNOME 45

[laurentlbm]

This version is not compatible with GNOME 44 and below. It will need to be uploaded as a separate version on extensions.gnome.org in order to keep the current, pre-45, extension available to those who need it.

Overview of the changes:

• Changed imports and exports to ESM
• Removed the use of ExtensionUtils (removed from GNOME 45).
• I changed IconProvider to no longer be a singleton. It needed to know the path of the extension, and since it couldn't have access to ExtensionUtils anymore, I decided to pass the path to its constructor. I decided that therefore it was safer for it to not be a singleton. Unfortunately, it meant having to pass it down: Extension -> Taskbar -> AppButton -> { AppButtonTooltip, AppButtonMenu }
• The GJS type WindowAttentionSource is no longer public, so I had to port some logic from the experimental branch in order to count notifications correctly.

Resources used for porting:

• Extensions in GNOME 45
• Port Extensions to GNOME Shell 45

Fixes #33

[ChepKun]

@laurentlbm wow man, you did a fantastic job, thank you!

[albert361]

Thanks for all of you, when could we find the new one on extensions.gnome.org?

[ChepKun]

@albert361 I'll submit the new version for review today

[JoaquinDecima]

Hi @ChepKun

It may be that the new version is not marked as compatible with gnome 45

[ChepKun]

@JoaquinDecima I've just made additional changes and submitted new version for review, hope to pass the review this time

[laurentlbm]

@JoaquinDecima Looks like it's been approved, Thanks @ChepKun !