Move terminal icon picker position to relevant terminal tab

[albarv340]

Fixes #211083
This moves the icon picker to always point to the terminal being affected by the icon change. If triggered via the command palette, the active tab is pointed to, since it is the one changing. If triggered via the terminal tab, it points to the terminal tab that is being changed.

Examples:
Change Icon was clicked on bash 1:

Triggered via action bar with bash 3 active:

[albarv340]

@microsoft-github-policy-service agree

[abhijit-chikane]

Well the question is if i try to update the color it opens up at the top and if I try to update the icon it is opening near the terminal tab, why two different choices?

[Narendherraj]

Like @abhijit-chikane has expressed his concern we should probably change the position of the terminal icon colour change tab as well if not it might look weird where one shows the position on bottom and the other on top .