Enhanced Terminal opening process

[sebjulliand]

Changes

Resolves #2359

When Code for IBM i opens a new Terminal, the TERM environment variable is now set to xterm.
The Terminal opening process has been refactored and enhanced a bit to:

• Add current directory as an optional property of the TerminalSettings type
• Wait until the Terminal is actually ready to fire events before doing anything
• Hide the initial commands sent to the terminal
• Display a nice message when the terminal is ready
  

How to test this PR

1. Open a PASE terminal from the bottom status bar
2. Open a PASE terminal by right-clicking on an IFS directory and select Open a Terminal here
3. Open a 5250 terminal

Checklist

• have tested my change

[github-actions]

👋 A new build is available for this PR based on 8df5d99.

• Download here.
• Read more about how to test

[worksofliam]

I checked out the branch but when I open the terminal it just hangs. I will continue to debug tomorrow.

[sebjulliand]

Hopefully that happened with the built VSIX, because the build started after the third commit, that fixes the terminal hanging when opened. I double checked and I can open the terminal without issue with the branch checked out.
If is still doesn't show for you, it would mean the open event is never triggered for some reason and I'll start to freak out.

[sebjulliand]

@worksofliam scratch that, the Terminal output is weird...the string is not always the one expected. See below, the "end tag" is messed up (doone instead of done).

I'll try to foul-proof it.

[sebjulliand]

@worksofliam it should be OK now.

[worksofliam]

@sebjulliand Look at that!

Gotta do one more test to confirm it works.

[worksofliam]

Merge whenever you're ready!

[sebjulliand]

Brilliant, thanks @worksofliam !