feat(glass): added glass theme - #7973

fixes #7972. I listed some acceptance criteria in the description of #7972 if you want to reference.

Compass with drawer demo to test - https://pf-pr-7973.surge.sh/components/compass/html-demos/with-drawer/

This adds

• .pf-v6-theme-glass - added to <html>, turns on the glass theme
• .pf-v6-c-drawer__panel.pf-m-no-glass - added to a pill drawer variant, disables glass styling when glass theme is enabled.

This PR creates these 4 tokens that can be used for theming

• --pf-t--global--[light/dark]--glass--background--color--glass--color
  • glass background color base. Takes any kind of color (uses color-mix())
• --pf-t--global--[light/dark]--glass--background--color--glass--opacity
  • glass background color opacity
• --pf-t--global--[light/dark]--glass--background--color--glass--filter
  • glass background (backdrop) filter(s)
• --pf-t--global--[light/dark]--glass--background--color--glass--default
  • this is used to set the combo of --color and --opacity above. If you theme it, it will override the --color and --opacity above. Maybe useful if you wanted to pass your own color function or something.

I used these values to test (you have to disable the --default vars for --color and --opacity to work)

--pf-t--global--light--glass--background--color--glass--color: red;
--pf-t--global--light--glass--background--color--glass--opacity: 50%;
--pf-t--global--light--glass--background--color--glass--filter: blur(5px) hue-rotate(180deg);
--pf-t--global--light--glass--background--color--glass--default: rgb(255, 255, 0, 0.5);
--pf-t--global--dark--glass--background--color--glass--color: green;
--pf-t--global--dark--glass--background--color--glass--opacity: 10%;
--pf-t--global--dark--glass--background--color--glass--filter: blur(2px) hue-rotate(90deg);
--pf-t--global--dark--glass--background--color--glass--default: purple;