Add bootrapping support for Linux/aarch64

[nightlark]

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Is your feature request related to a problem? Please describe.
Currently, bootstrapping and running vcpkg on an aarch64 Linux system requires using system binaries, including setting the VCPKG_FORCE_SYSTEM_BINARIES environment variable, which adds a bit of friction to getting vcpkg working.

Proposed solution
Looking through scripts/vcpkgTools.xml, I noticed it has download links for a number of tools but doesn't specify the architecture. The first (and biggest) step would be updating the file to include architecture information for each entry. If there are any actual x86 win32 users still out there, this could also enable giving a better warning when fetching the Windows ninja binary, which targets x86_64 and not win32 like most of the other binaries in the vcpkgTools file. With macOS migrating from x86_64 to aarch64, eventually new precompiled binaries might drop x86_64 support. I think adding an arch= variable and an explicit entry for each supported architecture would probably be easiest approach.

Some of the regex's will likely need adjusting to account for things like Universal binaries and backwards compatibility of win32 binaries on 64-bit Windows, though once it is done it could allow using newer precompiled binaries for x86_64 systems if precompiled binaries for an x86 system stop getting provided for new releases of a tool.

Some of the VCPKG_FORCE_SYSTEM_BINARIES environment variable checks will then need to get updated to reflect what architectures precompiled tools can be downloaded on.

From there, it would be waiting for the projects to provide precompiled binaries for aarch64 Linux, and helping some of them add aarch64 to their automated release builds.

Describe alternatives you've considered
Adding a way to construct the download url for different architectures would be interesting, but there is quite a bit of variety in naming conventions for download URLs, it makes knowing which platforms are available and which aren't more difficult to determine, and it becomes harder to maintain a list of sha256's for the downloads.

A partial approach could be taken where the extra info needed for aarch64 bootstrapping is added so it can fetch ninja+cmake, though it seems like still requiring the use of VCPKG_FORCE_SYSTEM_BINARIES in these cases would be kind of annoying.

Additional context
This is likely related to #3647

[VioletGiraffe]

At least please make the bootstrapping script complain about VCPKG_FORCE_SYSTEM_BINARIES not being set BEFORE I spend an hour compiling vcpkg on something like Raspberry Zero 2, so that I don't have to compile it a full second time as is the case right now.

[autoantwort]

Why you have to rebuild vcpkg-tool? Simply execute export VCPKG_FORCE_SYSTEM_BINARIES=1

[VioletGiraffe]

When you try to build it out of the box it first builds all the way or almost all the way and then tells you that VCPKG_FORCE_SYSTEM_BINARIES is not set. And when invoking the script the second time it starts building from scratch again.

[dg0yt]

Did vcpkg prompt you to run the bootstrap script again?
Downloading or building a fresh tool binary is the key purpose of the bootstrap script.