Brave Wallet as default wallet can be bypassed by extensions

[bbondy]

When a user selects Brave Wallet explicitly in chrome://settings/wallet, other wallets should not be able to make it writable then overwrite it. Tally Ho was one such wallet doing that

Steps to reproduce:

Test 1

i) Install Tally Ho extension https://chrome.google.com/webstore/detail/tally-ho/eajafomhmkipbjmfmhebemolkcicgfmd
ii) Go to brave//settings/wallet and select Brave Wallet as the default wallet.
iii) Open a new tab to any site
iv) Open Console and type window.ethereum.enable()

Expected:
Brave Wallet should show up

Actual:
Tally Ho shows up

Test 2

Repeat with Brave Wallet (Prefer Extensions) as the default wallet.
i) Use a new tab
ii) Ensure that setting is set
iii) Open Console and type window.ethereum.enable()

Tally Ho should continue to show up

[srirambv]

Brave	1.40.80 Chromium: 102.0.5005.78 (Official Build) beta (64-bit)
Revision	df6dbb5a9fd82af3f567198af2eb5fb4876ef99c-refs/branch-heads/5005_59@{#3}
OS	☑️ Linux	☑️ Windows 11 Version 22H2 (Build 22621.1)	☑️ macOS Version 12.0.1 (Build 21C52)
Verified steps from issue description Verified when wallet provider is set to Brave Wallet, running window.ethereum.enable() trigger opens Brave Panel Verified when wallet provider is set to Brave Wallet (Prefer Extensions), running window.ethereum.enable() trigger opens Extension Popup and not Brave Wallet Panel
	22678-Linux.mp4	22678-Windows.mov	22678-macOS.mov

[srirambv]

Removing OS/Android label as there is no way to switch Wallet provider and extensions are not supported on Android