Option to close an entire tabset

[srirambv]

• Did you search for similar issues before submitting this one?
  Yes

• Describe the issue you encountered:
  Option to close an entire tabset

• Platform (Win7, 8, 10? macOS? Linux distro?):
  All

• Brave Version (revision SHA):
  Brave 0.13.4
  rev 71d8ffc

• Steps to reproduce:

  1. Open the enough tabs to create a tab set
  2. Right click on the tab set
  3. Only option to mute/unmute tabs, no option to close all the tabs in that tabset

• Actual result:
  No option to close all tabs in a tab set

• Expected result:
  Would be nice to have a close tabs in the tabset option in context menu

• Screenshot if needed:
  

• Any related issues:
  cc: @bradleyrichter

[NejcZdovc]

This is a duplicate of #5489, PR is already ready #6570 and will be part of 0.13.5

[bradleyrichter]

This will be a great start to future tab-page options such as:

• close tabs in this page
• open these tabs in a new window
• new bookmark folder with these tabs
• lock this tab page