Prefer win64 full installer on /installer-help/ when appropriate

[amychurchwell]

Description

(bug 1564333)

Currently, when an user lands on https://www.mozilla.org/firefox/installer-help/?channel=release, they always get a win32 full installer, even if the stub installer finds their Windows OS to be compatible with win64 builds of Firefox.

┆Issue is synchronized with this Jira Task ┆Priority: (none) ┆Sprint: Backlog

[grininja]

I want to work on this issue

[ejregithub]

This appears to have been corrected. @Errolyn just tested with their Win64 bit build machine and found that the proper, expected Win64 bit build was provided.

[alexgibson]

As far as I know this was never fixed on the bedrock side, so I’m very curious as to how the 64bit build is being provided?

[ejregithub]

And blah . . . this remains, obviously. Thank you for confirming @alexgibson. I tested on my wife's Win64 bit and was provided the 32bit version of Firefox.

[alexgibson]

Depends on https://bugzilla.mozilla.org/show_bug.cgi?id=1621749

[alexgibson]

Bug https://bugzilla.mozilla.org/show_bug.cgi?id=1621749 has been fixed, so this is actually ready to work on I think!

The new installer_arch parameter should now provide the following hints to the /installer-help/ page:

1. if installer_arch=1 we should serve Windows 32bit installer.
2. If installer_arch=2 we should serve the Windows 64bit installer.
3. If installer_arch=3 we should serve the Windows AARCH64 installer.

If the installer_arch parameter is not present (i.e. unknown), we can assume to show links to the Windows 32bit installer.