Rename updateUrl to updateURL

This is to match standard naming conventions in the web platform.
Follow-up CLs will rename other *Url members of interest group and ad
auction configs.

Both naming conventions will need to be supported for a time, to allow
sites to transition. To further aid transitioning, for a given
dictionary field, if both the fooUrl and fooURL versions are provided,
no error will be issued if both versions have the same value.

NOTE: Support for the previous old name, dailyUpdateUrl, continues and
remains unchanged.

These are the sites that need to support the old and new names -- they
each have tests to ensure that both new and old names work (currently,
the updateURL cannot be updated by interest group updates):

1. joinAdInterestGroup() (in Blink)
2. Interest groups passed to the bidder worklet

Bug: 1432707
Change-Id: I2b7d47568101c9192d8ed1933dc23248bfa5ec55
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4549365


Commit-Queue: Caleb Raitto <caraitto@chromium.org>
Reviewed-by: Maks Orlovich <morlovich@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1147348}