Update Status Bar `terminal` icon to `terminal-powershell` icon

[TylerLeonhardt]

As of 1.56 (current latest as of the creation of this issue), there is a terminal-powershell codicon!

Feel free to use it everywhere, but a good spot for sure would be replacing terminal here with terminal-powershell:

vscode-powershell/src/session.ts

Line 659 in db40d97

let statusIconText = "$(terminal) ";

[andyleejordan]

Thanks @TylerLeonhardt!