When compiled to `GOOS=js`, wasm does not maintain the working
directory: it is defined by the host. While not explicitly documented,
`os.TestDirFSRootDir` in Go suggests the working directory must be valid
to pass (literally the directory holding the file).
This adds an experimental CLI flag that gives the initial working
directory. This is experimental because while GOOS=js uses this, current
WASI compilers will not, as they maintain working directory in code
managed by wasi-libc, or as a convention (e.g. in Zig).
It is not yet known if wasi-cli will maintain working directory
externally or not.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
7e953d7483