Remote control and P2P access

[LossyDragon]

Description

Draft for now as P2P connection isn't working right now.

This PR implements the following:

• Update RPC proto parser to accept webui protobufs.
• Added SteamClientCommunication which uses service_clientcomm.proto class which contains methods to control a steam client, such as remote download. remote launch a game, etc.
• Add remaining methods found in the ContentServerDirectory rpc block.
• Add kdoc with known descriptions of the new methods after testing what they do.
• Update Known Unified Services test.

Checklist

• [ ] Code compiles correctly
• [ ] All tests passing
• [ ] Samples run successfully
• [x] Extended the README / documentation, if necessary