[lldb] Refactor DIL to take and store the context in `ExecutionContext` (#225849)

This patch rewrites DIL to take, store and use `ExecutionContext` for
calls that require context, instead of `StackFrame` and `Target`
separately. This is a step towards being able to run DIL without
`StackFrame`, although this won't work just yet since DIL relies on
`StackFrame` to retrieve the current compile unit and type system.

GitOrigin-RevId: 76cfafe3f8812a9abe1f477844f313ae16d83f61