Replace WebAssembly feature CLI options with --wasm-features.

This commit hides the existing WebAssembly feature CLI options (e.g.
`--enable-simd`) and adds a `--wasm-features` flag that enables multiple
(or all) WebAssembly features.

Features can be disabled by prefixing the value with `-`, e.g.
`--wasm-features=-simd`.

Cargo.lock

@@ -3273,6 +3273,7 @@ dependencies = [
  "file-per-thread-logger",
  "filecheck",
  "humantime 2.1.0",
+ "lazy_static",
  "libc",
  "log",
  "more-asserts",