Replace bare remote type strings in C++ process-selection plumbing with
a RemoteType type which stores the parsed kind, isolation URI, and
process selection attributes directly.
This preserves the existing serialized string form for IPC and JS-facing
APIs, while making native callers use explicit predicates and structured
fields instead of manually parsing remote type prefixes and suffixes.
No JS-exposed API for parsing or otherwise interpreting remote types are
currently exposed in this patch. My current expectation is that this
will likely look like a `nsIRemoteType` interface which wraps this
`RemoteType` value type, exposing helpful getters for JS callers.
Differential Revision: https://phabricator.services.mozilla.com/D310442
Nika Layzell
c51090b135