Bug 1879792 - Add a cookie banner to BMO

[dklawren]

From bug:
We should include a Cookie Banner on BMO to reduce our exposure to legal risks from changes in EU and US privacy law of the last several years.
BMO has a number of non-essential cookies that improve the UX of the site. Even though these non-essential cookies are not used for tracking purposes, Legal have advised that a cookie banner is still warranted.

• This pull request uses JS code written by the web team for use in Mozilla web properties that I have vendored into the codebase since we do not use webpack.
• I updated the BMO JS to also not set keys in localStorage if cookie consent is rejected.
• The changes also look at a special header that is already included by CloudOps which has the region code for the client. If the region is in the whitelist then it will show the banner, otherwise all works as before.
• GoogleAnalytics code is removed completely as we do not use it anymore.
• There is a new input in the user preferences to turn on or off cookie consent even after clicking the banner.

Let me know if you have any questions