Merge functionality of blur-providers extension in to this one

[CorvetteCole]

This draft PR will track the progress of work to port the existing application blurring functionality of the blur-provider extension to blur-my-shell.

Beyond simply porting existing functionality, several other changes need to be done. These have been summarized below:

• Port existing application blurring on X flag functionality
• Improve Wayland support (Wayland support CorvetteCole/blur-provider#2) (needs testing!)
  • Figure out a way for applications to request blur beyond X flags. (e.g. an application not running within XWayland or X
• Add manual user application selection for blurring (Making blur persistent CorvetteCole/blur-provider#3)
  • Add application selection to the extension settings
• Keep blur behind target actors in overview (right now it just kind of disappears)
• After switching to a workspace and back, blur appears on top of the target actor until the screen is interacted with Fixed In Gnome 40
• When switching focus rapidly between windows, blur can blink in front of all windows briefly Fixed In Gnome 40

[CorvetteCole]

blur-provider is still working perfectly in Gnome 40 (although the settings menu does not work). This is great news, initial port should be relatively easy. Additionally, several of my largest bugs with the blur effect were fixed in Gnome 40. This is shaping up to be an awesome addition!

[aunetx]

This looks really great :)

[CorvetteCole]

I am opening a new pull request from my new applications-blur branch so we can keep track of things easier. See #39