[Desktop] open reduced brave://settings in Tor rather than opening in regular window (match Guest windows)

[kjozwiak]

Description

When we currently open brave://settings in a Tor window, we currently do the following:

• switch to an already opened brave://settings tab in a normal window
• if brave://settings isn't opened, open a new tab and focus that tab in a normal window

Guest windows have their own brave://settings as per the following:

We should implement the same for Tor windows. Probably not a high priority though IMO. @rebron can close this off we we're not interesting in matching Guest windows. Issue was spawned from a discussion on Slack re: #5065 (comment).

Steps to Reproduce

1. launch brave and open a new Tor window
2. open Settings via the hamburger menu or loading brave://settings

You'll notice that brave://settings are opened in their own window.

Actual result:

Opening brave://settings in Tor opens them in a regular window.

Expected result:

Match Guest window and have a limited amount of brave://settings for Tor

Reproduces how often:

100% reproducible using the above STR.

Brave version (brave://version info)

Brave | 1.11.92 Chromium: 84.0.4147.68 (Official Build) dev (64-bit)
-- | --
Revision | e7b7234037639b407e69c5428c891ce018cd6c0d-refs/branch-heads/4147@{#772}
OS | macOS Version 10.15.5 (Build 19F101)

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the dev channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? N/A
• Does the issue resolve itself when disabling Brave Rewards? N/A
• Is the issue reproducible on the latest version of Chrome? N/A

Miscellaneous Information:

CCing @bsclifton @petemill @LaurenWags @rebron.

[rebron]

We have a related issue with #10567. In that one, the hamburger menu Settings link goes back to a normal window which implies no settings for Tor while the keyboard shortcut ("cmd + ,")goes to a Tor settings page that exhibits some strange behavior, e.g. a change to search engine and then a follow-up query happens on a normal window and no changes affect the Tor window profile.

[rebron]

cc: @darkdh @yrliou