Update the regex for the PowerShell parser

[daxian-dbw]

Update the regex for the PowerShell parser:

1. Support matching the PowerShell cmdlets and parameters;
2. For operators, update the regex to match pipeline operator | and the array literal operator ,;
3. For attributes, update the regex to match more available attributes;
4. Make attribute and keyword matching case insensitive;
5. Add pwsh as an alias for the PowerShell language;
6. Add the color setting for PowerShell command and parameter for both the default dark and light themes.

[daxian-dbw]

@michael-hawker Could you please do a code review? Thanks!

[daxian-dbw]

Gently ping. @michael-hawker @azchohfi, can you please review this PR? Thanks!

[michael-hawker]

Sorry, I was away. @daxian-dbw do you have a before/after picture of the changes on a PowerShell file? Otherwise, appears good!

[daxian-dbw]

@michael-hawker No worries!
Here are the screenshots to show the highlighting before and after the changes:

Before the change

After the change

[daxian-dbw]

@michael-hawker gentle ping :) Can you please review again? The pictures were added.

[Arlodotexe]

The case sensitivity for keywords was fixed, Commands and Parameters are now highlighted, and several more inbox attributes are now supported (case insensitive). No obvious issues. Approved 👍

[daxian-dbw]

@Arlodotexe and @michael-hawker, thanks for the review!