Make vertical build defines of Host and Target properties explicit

[mmitche]

When building in CI/Official and PRs, we should make our Host and Target properties explicit on the command line:

• HostArchitecture
• TargetArchitecture
• HostOS
• TargetOS
• HostRid
• TargetRid

Much of the time, many of these properties will match. But there is quite a lot of implicit behavior when inferring them in dev scenarios.

[mmitche]

See dotnet/installer#18658 for extended conversation on this topic.

[tmds]

note: TargetOS as how the runtime repo uses it is not the 'os' part of the TargetRid. For non-portable Linux builds, linux-bionic, and linux-musl, TargetOS is linux. And on Windows, it is windows instead of win.

[tmds]

TargetOS as how the runtime repo uses it is not the 'os' part of the TargetRid.

The same is true for TargetOS in the vmr.

Having a property that contains the 'os' part of the TargetRid wouldn't be very useful to have. TargetRid is just the name for what gets built.

TargetOS (as we have it) tells us something meaningful about the target: the target is Linux.

[ViktorHofer]

as how the runtime repo uses it is not the 'os' part of the TargetRid. For non-portable Linux builds, linux-bionic, and linux-musl, TargetOS is linux

Right, @directhex mentioned that in the past. Ideally TargetOS would be the full OS string, i.e. linux-musl or linux-bionic. We will always have one special case for windows vs win and I think that's fine. It would be good to eventually clean this up in runtime and also make the runtime build use the correct properties (build vs host vs target).

[ViktorHofer]

This is now already implemented for the Target* properties. We didn't see a need to also flow the Host properties in so far. The repos that need them currently calculate them individually. I think we can close this.