Enable semanticHighlighting in PowerShell ISE theme

[aeschli]

Since 1.43, VSCode themes can take advantage of semantic highlighting.

Every theme controls whether semantic tokens are enabled. So far, only built-in themes have it enabled and I filed this issue to ask you to opt-in for the PowerShell ISE theme as well.

Adoption is easy and there are new cool styling possibilities.

To turn on semantic highlighting for you theme, all you have to do is put
"semanticHighlighting": true
in the theme definition file.

There's a good chance that no further change to the theme is needed (thanks to a default mapping from semantic tokens to TextMate scopes (if not, I'd be interested to know, so I can improve the defaults further)).

But, more interestingly, themes can tune and go wild by defining new styling rules against the semantic tokens:

"semanticTokenColors": {
    "variable.readonly": "#ff0000", 
    "parameter": { "fontStyle": "underline" },
    "*.declaration:java": { "fontStyle": "bold" }
} 

Check out our Semantic Highlighting Wiki and the Semantic Highlighting Guide for more details and feel free to ping me in this issue if I can help.

[TylerLeonhardt]

Just for clarity - this is to support languages that support semanticHighlighting, yes? Not to support semantic highlighting in PowerShell (which we also wanna do when the LSP API is stable)

[aeschli]

Right, this is actually just for the theme (I'm contacting all the top theme authors).
If your theme only make sense to be used with Powershell, then you can ignore the request until Powershell also has semantic highlighting.

[TylerLeonhardt]

Fixed in #2834