Add wasm32v1-none support

[daxpedda]

Changes:

• Add default-features = false to the js-sys and wasm-bindgen-test dependencies, enabling no_std support.
• The crate feature std now enabled std crate features of wasm-bindgen, js-sys and wasm-bindgen-test.
• Use any(target_os = "unknown", target_os = "none") instead of target_os = "unknown".
• thread_local! is only supported with std, so a fallback to static with once_cell::unsync::Lazy is added. This is safe because Wasm doesn't support threads without target_feature = "atomics".
• When detecting target_feature = "atomics" without feature = "std", use #[thread_local].
• Now wasm32-unknown-unknown is properly supported without pulling in std.

I was unable to add actual no_std tests without some ugly modifications to it. Especially because of the whole harness = false thing. Let me know how you want me to proceed.

This depends on rustwasm/wasm-bindgen#4277 and a new wasm-bindgen release.

[daxpedda]

Current CI failure is unrelated.

[newpavlov]

The CI failures are fixed in #542.

[daxpedda]

Hm, CI still has an unrelated failure.

[newpavlov]

Yes, see rust-lang/rust#133401. We may disable the GNU/Hurd job since it's not the first time the std breaks this target.

UPD: Fixed in #543.