Specify virtual platform version and enforce it

VM config can now specify the requirement on the virtual platform
version. At runtime, the requirement is matched against the actual
virtual platform version that crosvm implements. If they don't match,
the VM can't be created. The version format follows SemVer, allowing us
to express backwards compatible and incompatible changes in the future.

Bug: 193504487
Test: atest VirtualizationTestCases
Change-Id: I23d370081e10399502178b9cfe8a46b05addf186