WIP: add yarn support for package install

[olingern]

Explain the motivation for making this change. What existing problem does the pull request solve?
Fixes #11122

Test plan (required)

• Init / Install without Yarn installed on system (force npm). Ensure install does not mix Yarn / npm if Yarn is available after installing with npm.
• Init / Install with Yarn installed on system. Ensure install continues to only use yarn.

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[n3tr]

Hi @olingern, I'm working on adding Yarn support for cli as well. please check it out #11174 :)

[olingern]

@n3tr Awesome! Sorry, I didn't see anything in #11122 mentioning you were on it. All yours :)

[n3tr]

@olingern sorry, it was my mistake 😢. I haven't carefully checked for the issue and just realized when you mentioned to it.