This Azure Pipelines setup compiles and tests Wasmtime for Linux, macOS, and Windows.
If the CI run was triggered by a new tag being created, a new release for that tag is created with a changelog relative to the last tag release and archives of the builds for all platforms.
If the CI run was triggered by new commits landing on `master`, the release `latest-master` is updated with a new changelog relative to the last tag release and archives of the new builds for all platforms.
Note: This PR also contains changes to disable a bunch of tests on Windows, which are failing due to issues with signal handling.
wasmtime-execute is now wasmtime-jit. Move `JITCode` and the TargetIsa
into a new `Compiler` type. `InstancePlus` is no more, with trampoline
functionality now handled by `Compiler`.
And lots of other miscellaneous changes. Rename InstanceWorld to
InstancePlus and reorganize its contents. This still isn't a great name,
but at least now it has a clear purpose.
