Repository list minimize should be more clear

[pqua613]

When the repository list is initially formed, the list is sorted into tabs. However, there is no indication that minimising is even possible. A symbol of some kind or any other indication should be displayed and used to minimise the tabs instead of the user finding out by accident and wondering where their repository list has suddenly disappeared to.

Steps to reproduce:

• Log in to Visual Git
• Click the repository button in the top right
  
• Click the forked list label (e.g. ↨kblincoe/VisualGit_SE701_2019_3 (Forked List))
• Observe the minimised list

NOTE: This will not work if you search with a search term and search again after clearing the search term as the forked list label will disappear. This is likely to be resolved by issue #251 and may, therefore, depend on it.

Before:

After:

[AmanDwivedi02]

Is the double arrow not enough?

[pqua613]

It's in such an obscure position that it's really hard to tell that it even exists

[Pathical]

Approve

[AmanDwivedi02]

That's fair I guess, approve.

[BennyChun]

Approve