[SDL 0315] Add RPC Conflict Management

[jordynmackool]

Proposal: Add RPC Conflict Management

This proposal is to add a function to SDL Core that manages concurrent RPC conflicts according to priority. This will allow OEMs to receive the expected request from SDL Core during RPC conflict by modifying the configuration in the policy table in which the priority is set.

Review: smartdevicelink/sdl_evolution#1068

Steering Committee Decision:

The Steering Committee voted to accept this proposal with revisions. The author is to update the proposal to include the agreed-upon revisions in this comment (which include modifying table 3, and the sentence following it).

The proposal .md file was updated to reflect these revisions on 2021-03-18.