Windows: integrate libwasmvm into Go code and test Go project on Windows

[webmaster128]

This is a follow up work of #338. Thank you very much for pushing that and showing how it can be done. I took a lot from over there.

In the meantime we pulled out a bunch of blockers and fixed them separately:

• Change filesystem errors to be consistent across operating systems cosmwasm#1406 removed the OS specific file system errors such that we reduce the rist of non-determinism and don't have to bother about the error message in our test code
• assert_approx_eq macro for nicer testing #352 and Copy assert_approx_eq to cosmwasm_std::testing cosmwasm#1417 make the test code more resilient to OS specific nuances, which helps this repo in other places as well (e.g. Intel vs. M1 CPU on Mac)

Closes #371

• Add libwasmvm testing (Rust) on Windows
• Add wasmvm testing (Go) on Windows
• Return error as integer in remove_wasm
• Use CachePtr for remove_wasm

[webmaster128]

No windows support planned for the time being