Allow a terminal creation to ignore VSCode's process environment

[GabeDeBacker]

#64731 - > Allow a terminal to be created with a specific environment by not inheriting VSCode's environment.

[Tyriar]

@GabeDeBacker we just had the API call, the idea is approved and the final incarnation we landed on is pretty simply and much closer to the initial version:

export interface TerminalOptions {
    /**
     * Whether the terminal process environment should be exactly as provided in
     * `TerminalOptions.env`. When this is false (default), the environment will be based on the
     * window's environment and also apply configured platform settings like
     * `terminal.integrated.windows.env` on top.
     */
    strictEnv: boolean;
}

If that works for you we can keep working on the PR and merge it in.

[GabeDeBacker]

Sorry, didn't mean to go missing in action here. I'll get on this and get it completed with the approved API design above.

[Tyriar]

LGTM, works great. Merging after CI passed 😃