after tipping, the banner does not have good keyboard accessibility

[LaurenWags]

Description

After you tip, the "thank you" message is in-line on the tip banner in 1.2.x and above. However, after tipping there is no element highlighted (showing a box around it) to indicate that it is active on the tip banner. This is necessary for accessibility so users can know where they are on the banner. If you tab a bit eventually something will get highlighted, but then you encounter #6986 and leave the tip banner, unable to return via tab.

Steps to Reproduce

1. Have rewards enabled and BAT in your wallet.
2. Go to a verified publisher.
3. Open tip banner.
4. Tip site (note, thank you is "in line" in 1.2.x and above)
5. Thank you message is displayed where the tip amounts were.

Actual result:

Nothing on the tip banner is highlighted w/ a box to indicate where you are - same occurs for both monthly and one time tips:

Expected result:

Something should be highlighted and user selectable via keyboard - perhaps the Share option? This is for product to determine.

Reproduces how often:

easily

Brave version (brave://version info)

Brave	1.2.41 Chromium: 79.0.3945.88 (Official Build) (64-bit)
Revision	c2a58a36b9411c80829b4b154bfcab97e581f1f3-refs/branch-heads/3945@{#954}
OS	macOS Version 10.14.6 (Build 18G103)

Version/Channel Information:

• Can you reproduce this issue with the current release? 1.1.x it is n/a, but yes for 1.2.x
• Can you reproduce this issue with the beta channel? probably
• Can you reproduce this issue with the dev channel? probably
• Can you reproduce this issue with the nightly channel? yes

Other Additional Information:

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

Miscellaneous Information:

cc @mandar-brave @alexwykoff