Side panel button missing

[Yiannis128]

Description

The sidebar button and option in brave flags are missing the side panel options.

Steps to Reproduce

1. Go to Brave flags
2. Search for side panel
3. No side panel option to enable.

Actual result:

Expected result:

Expect a listing to enable side panel button in the header area of the browser.

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

1.39.111 Chromium: 102.0.5005.61 (Official Build) (64-bit)
0e59bcc00cc4985ce39ad31c150065f159d95ad3-refs/branch-heads/5005@{#819}
Linux

[bsclifton]

cc: @petemill

[bsclifton]

Closing as this is now implemented and the button is showing for folks 😄 We have an issue to allow for toggling the button here:
#25272