Launcher

[martinfouilleul]

This introduces major changes in the distribution model of both the Orca tooling and Orca apps:

• Orca apps are now bundled by default as .orca files that contain only the WebAssembly modules and the app's resources. (You can still bundle standalone apps if needed by passing the appropriate flag to the CLI tool.)
• The runtime, SDK and tooling are distributed as a single package (an Orca.app bundle on macOS, and an application folder with all executables, DLLs, etc on Windows). This can be used as a CLI, or run without argument / double-clicked to open a GUI launcher (still a work in progress)
• .orca files can be run by the orca runtime, either invoked from the CLI or launched from the GUI.

This PR also introduces several related changes to the following APIs or internal systems, including:

• More complete file API to support filesystem operations needed by the new tooling. This includes functions to create/remove/copy temporary or persistent files and directories.
• Modified UI layout to support layouting needs of the launcher UI, and fix some quality of life issues.
• The interface definition files used to generate bindings of native functions to wasm imports were combined and updated to use the same schema as the API description files used to generate the documentation. The was we bind wasm imports is also simplified to put all the "host calls" in one place and avoid excessive marshalling of structs.
• Fixes to invalid wasm modules handling (pass all assert_invalid tests).
• Subprocess API to support the launcher (native-only).
• CLI argument parsing helper for the tooling.
• Fixes to path handling.
• count in oc_list
• Testing helpers and updated tests.