SWIG: rename internal module which imports SWIG wrappers to _lal..._swig

Detailed Description

TLDR: The SWIG Python wrappers are internally loaded as follows, e.g. for LAL:

1. an internal module _lal (actually a compiled .so library) containing the wrappers is loaded by
2. an internal helper module lal.py (generated by SWIG), which is then loaded by
3. the base Python module lal (defined by lal/__init__.py).

A side effect is that the SWIG wrappers exist under the module lal.lal (the internal helper module) in addition to lal (the base Python module). To obscure the internal helper module, this MR renames it to _lal_swig, the leading underscore making it clear that this module is internal.

This does not change the public Python API in any way; all public symbols are still available under the lal namespace.

(Rinse and repeat for the other libraries.)

API Changes

Please tick one of the following options:

• These changes do not modify the API.
• These changes do modify the API, and are backwards compatible.
• These changes do modify the API, and are backwards incompatible.

For examples of changes that do not modify the API and/or are considered backwards (in)compatible, please see the contributing guide.

Justification for Backwards Incompatible Changes

Review Status