[Environments] Extension Refresh & other fixes

[huzaifa-d]

Summary of the pull request

1. Bug fix - Fixes "Create Environments" button showing cached extension availability.
   Using the button after enabling extensions, didn't refresh the page and didn't show data from the enabled extension.
   The PR removes the caching code and refreshes the page every time navigated to.

2. Bug fix - Fixes adding incorrect user to Hyper - V admin group.
   Adding a user to the Hyper-V admin group runs an elevated script. And getting the current user in this script returns the admin.
   The bug was that the admin was being added to the group, not the user who might have initiated the operation. The fix adds the user as a parameter to the script call.

3. Bug fix - Hides browse button under repo manager for remote machines.
   Having a browse button, while configuring remote machines, was confusing as it browsed the local machine instead.
   The PR hides the button in cases where remote machines are being configured.

4. Bug fix - Machine config page doesn't load extension data
   If one of the accounts associated with an extension errored out, an exception caused the rest of the data to be skipped.
   The PR removes the data with the errors from the relevant variable, since it has already been handled.

Validation steps performed

Each fix was tested manually.

PR checklist

• Closes disabled all extensions but create environment shows dev box + hyper-v still #3353
• Closes [Environments reliability] Hyper-V Operations: Can't add standard user account to Hyper-V Administrator group if elevating using a separate administrator account #3112
• Closes Browse button when cloning to Environment browses local machine #3219
• Closes [Machine Config] Dev Boxes not loading if multiple accounts logged in #3568