fix(hosting): mark app-type and hosting-product as required in help - #345

Summary

--app-type and --hosting-product are required, but --help listed them like optional flags. This labels them "(required)" in their help entries and adds a test so the label stays in place.

Why

The API requires appType and hostingProduct, and the CLI rejects a missing value. The usage line shows the flag outside [OPTIONS], but the options block gave no sign of it. --app-type was also described as "Hosting product", which reads like --hosting-product on the other command.

Changes

• --app-type on hosting app list and hosting app create, and --hosting-product on hosting subscription list, now read "(required)" in --help.
• --app-type is described as the application type. The hosting app group help says "application type" too.
• The hand-written "is required" sentences are removed from the app list and subscription list descriptions. The value list copied by hand into --hosting-product is removed as well, since clap prints the possible values itself.
• A new test runs app list, app create and subscription list without the flag. It checks that each fails and that its --help entry says "(required)". The CLI helpers it uses moved from the app create tests into hosting/test_support.rs.

Not in this PR

Other feedback suggested two things, and neither of them is included here.

• Listing the allowed values when a required flag is missing. Clap builds that error and cli-engine prints it as is, so this needs a change in cli-engine. An invalid value already lists the options.
• Dropping the flag, or defaulting it, when only one value is eligible. MHWP is behind a feature flag. Once it is on, hosting app list with no flag would either fail or default to NODEJS and hide WordPress apps from the list, so I kept the flag required. This one is open for discussion.

Tested

Run on this branch:

• cargo fmt --check
• cargo clippy --workspace --all-targets -- -D warnings
• cargo test --workspace
• check-module-size.sh