Add related error spans for getter/setters with different types

Now that we support multiple related spans for errors (#10489, #22789, #24548), we'd like to improve an existing error message.

Currently, we provide a diagnostic for a pair of get/set accessor's types not matching:

Code:

let x = {
  get foo() { return 100; }
  set foo(value: string): { }
}

Current error:

'get' and 'set' accessor must have the same type.

We'd like to give a better error message. For example:

Primary span:

A 'get-' and 'set-' accessor must have the same type, but this 'get' accessor has the type '{0}'.

Related span:

The respective 'set' accessor has the type '{0}'.

The issue names no files or tests; start by locating the TypeScript typechecker diagnostic for mismatched get/set accessor types and tracing its diagnostic-span handling. Done means the primary diagnostic reports the getter type, a related span reports the setter type, and coverage verifies the displayed messages and spans.