Fix 'peek inside peek' when opening definition link

[GustavoASC]

This situation has been discussed on PR #89884.

• VSCode Version: Code OSS Dev (Insiders hasn't been built since PR Developed setting which controls whether the definition link opens element in the peek widget. #89884)
• OS Version: Ubuntu 19.10

Steps to Reproduce:

1. Check the new setting 'Definition Link Opens in Peek'

2. Use ctrl + click to open definition on Peek Widget
3. Inside that Peek Widget use ctrl + click again on another definition.

As can be seen on this image there will be nested peeks which is not a correct behavior.

I will submit a new PR because I have already fixed this on my fork.

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Peek Definition menu option missing in the "Peek Definition" window (#27128)
• allow for cascading peek (#6857)
• Nested peek definition (#35608)
• Peek widget is not closed when search term is changed in search editor (#89449)
• Exposing API for the peek diff window (#86312)