Implement WASI initial cwd configuration

[angelnereira]

This implements the missing configuration path for wasi:cli/environment.initial-cwd discussed in #9695.

Summary:

• add WasiCtxBuilder::initial_cwd to configure the value reported by wasi:cli/environment.initial-cwd
• add -Scwd= and wire it into the CLI's WASIp2 context setup
• add an end-to-end CLI test component that verifies the guest observes the configured cwd

Tests:

• cargo fmt --all -- --check
• cargo test -p wasmtime-cli-flags from_toml
• cargo test -p wasmtime-wasi --lib initial_cwd
• cargo test -p test-programs --target=wasm32-wasip1 --no-run --bin p2_cli_initial_cwd
• cargo test -p wasmtime-cli --test all p2_cli_initial_cwd
• cargo check -p wasmtime-cli
• cargo clippy -p wasmtime-cli-flags -p wasmtime-wasi --lib

[alexcrichton]

Thanks!

[alexcrichton]

For this it's best to skip the test here and rely on testing in cli_tests.rs instead. Given that, can you remove this?

[angelnereira]

Makes sense, thanks for the guidance. I’ll remove these low-level checks and keep the coverage at the CLI/end-to-end level.

[alexcrichton]

There's no need to add these tests, we don't typically test at this micro-level of granularity. The end-to-end tests are fine. (it becomes extremely onerous to refactor if tests are there for every possible behavior and implementation detail of a function)

[angelnereira]

thanks. I’ll remove these micro-level tests and keep the behavior covered at the end-to-end level.