Add support for 100 tabs

[cezaraugusto]

Test Plan:

• Clear session
• Go to preferences->tabs
• Default should be 20
• Opt for 100 tabs
• Open 100 tabs
• Tabs should resize accordingly

Description

Fix #6692

Note: this PR also sets default number of tabs per page to 20

Auditors: @bbondy, @bsclifton

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

[bsclifton]

Had to share this- here's 100 tabs open on my 27" Thunderbolt monitor 😄

[bsclifton]

Tested it out, everything works great 😄 As shown in the screenshot, I actually had over 100 tabs open. I got the RAM usage up to 11 GB!! (who knows how many videos were playing at the same time)