Internal debug UIs: Change implementation of pages behind pref, non-iOS

Overriding CreateWebUIController() results in a mismatch in bindings
when the user toggles the pref in chrome://chrome-urls and then uses
forward/back navigation to return to a debug UI. This is because
forward/back navigation requires state restoration for debug WebUI
pages. The mismatch in bindings causes a crash.

This CL instead has ChromeContentBrowserClient rewrite any debug UI
URLs (still tracked via InternalWebUIConfig) to
chrome://debug-webuis-disabled?host=hostname, where hostname is the host
of the debug WebUI. The InternalDebugPagesDisabledUI is served from
chrome://debug-webuis-disabled instead of being served from the
debug UI URLs directly.

A script is added to the internal debug pages disabled UI that
redirects to the debug page if the disabled UI is served when the
InternalDebugPagesEnabled pref is set to true. This is so that
navigating back after enabling debug UIs in chrome://chrome-urls
will appear to work correctly. Navigating back to a previously
enabled UI after disabling the UIs in chrome://chrome-urls will still
serve the original UI; a solution to this issue is TBD, but it is
less likely to impact users.

Note that iOS did not use the same implementation of this pref since
WebUIConfig is not used on iOS. The iOS implementation is unaffected
by this change.

Bug: 404788318
Change-Id: I1a007ed466776235963aa35e08894cd1cf923b09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6551440
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Sarah Krakowiak <skrakowi@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1462452}