[lldb] Fix Windows linker error for MakeSBModuleSpec in lldb-server (#181494)

## Summary
Move the definition of `ScriptInterpreter::MakeSBModuleSpec` from
`ScriptInterpreter.cpp` to `ScriptedPythonInterface.cpp`.

`MakeSBModuleSpec` constructs an `SBModuleSpec`, whose symbols live in
the API library (`liblldb`). `ScriptInterpreter.cpp` is part of
`lldbInterpreter`, which is also linked into `lldb-server` — and
`lldb-server` does not link the API library. On Windows, this causes
`LNK2019: unresolved external symbol` for `SBModuleSpec`'s constructor
and destructor.

`ScriptedPythonInterface.cpp` is part of the Python plugin library,
which only links into `liblldb` where the API symbols are available. The
method retains friend access to `SBModuleSpec` since it is still a
member of `ScriptInterpreter` regardless of which `.cpp` file defines
it.

Fixes Windows linker failure from #181334.

## Test plan
- [ ] Existing ScriptedSymbolLocator tests pass

Co-authored-by: Rahul Reddy Chamala <rachamal@meta.com>
GitOrigin-RevId: de4f473f884e1b59378bf04d37023f6fc7f3601a