Add option to make audio icon non-clickable

[rebron]

Description

When users have many tabs, many prefer that the audio icon in tabs are non-clickable. A non-clickable audio icon is the default behavior in Chrome and finding tabs that have audio and controlling that audio was solved via the media menu/controls. We should introduce a feature flag to allow users to be able to toggle the functionality of the icon from clickable to non-clickable.

We'll use:
brave://flags/#tab-audio-icon-interactive

Steps to Reproduce

1. Open a website that has audio or video content and play the content e.g. YouTube or npr.org.
2. Notice the audio icon in tab.
3. Click to mute or unmute the tab.

Expected result:

Go to brave://flags and find the tab-audio-icon-interactive flag. Toggle the flag, repeats STR and notice that the audio icon is no longer clickable and can no longer mute/unmute the tab.

Reproduces how often:

n/a

Brave version (brave://version info)

Version/Channel Information:

• Can you reproduce this issue with the current release? n/a
• Can you reproduce this issue with the beta channel? n/a
• Can you reproduce this issue with the nightly channel? n/a

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:

[kjozwiak]

Moving this into 1.34.x as per the discussion we had on Tuesday's b-b meeting. It doesn't seem like we'll get another C96 before we release 1.34.x with C97. However, if we do end up getting another C96 and it ends up fixing a zero day security issue, we'll re-create a 1.33.x - Release #2 milestone and move this issue back as it's already in the 1.33.x branch.

[stephendonner]

Verified PASSED using the steps from brave/brave-core#11468

Brave	1.34.76 Chromium: 97.0.4692.56 (Official Build) (x86_64)
Revision	04da6c66398ca50e603cc236a07dc7dfd3bbc750-refs/branch-heads/4692@{#990}
OS	macOS Version 11.6.1 (Build 20G224)

Steps

Disabled state

1. Set tab-audio-icon-interactive flag to Disabled in brave://flags and restart browser
2. Play some audio in a tab
3. The audio icon should still show
4. The audio icon should not be clickable, or have a hover state

Confirmed the icon isn't clickable, with no hover state.

example	example

Enabled state

1. Set tab-audio-icon-interactive flag to Enabled in brave://flags and restart browser
2. Play some audio in a tab
3. The audio icon should show
4. The audio icon should be clickable, and have a hover state

Confirmed the icon is clickable/toggle-able, with a hover state.

example	example	example	example