tool_build/package_compiler: renamed _metadata to _manifest.
tool_build: inherit from ResourceMetadata in ResourceCompilerMetadata.¹

1: No More Hacks (POD constraint change allowed this).
tool_build/package_compiler: moved compiler metadata (format 3).¹

1: Want ResourcePackage to be able to read an unpacked manifest,
so the compiler metadata properties are moved to the segment
following _manifest (the metadata array).
tool_build/package_compiler::create_stub(): build_parity is a bool.¹

1: Why is this a thing, again? String literals? Yuck.
tool_build/package_compiler: split compiler metadata into separate file;¹ tidy.

resource: added SER_FORMAT_VERSION_PKG_MANIFEST.

1: Welp. The formats shouldn't intermingle, so now they're separate.
resource: added class for compiled path; merged resource_metadata.
filesystem: added file_size().
tool_build/package_compiler: mark properties as modified when true.
tool_build/package_compiler: added build().
tool_build/interface: added pack command.