[sdb] Add command CMD_STACK_FRAME_GET_DOMAIN

This command returns the domain in which the stack frame is executing

Bump protocol version.
[Mono.Debugger.Soft] Implement StackFrame.Domain

This property uses the new CMD_STACK_FRAME_GET_DOMAIN command
to retrieve and cache the domain in which the stack frame
is executing.

Bump the protocol version to match the runtime.
[Mono.Debugger.Soft] Add test for StackFrame.Domain

Assert that the property returns the proper domain for the stack frame.
Merge pull request #1411 from jbevain/sdb-frame-domain

[sdb] Expose the domain of the stack frames