Restructure binary distributions for subpackages

Based on a desire from @kipp.cannon in !1058 (closed) I would like to float the following reorganisation of the binary packages built for each of the subpackages of lalsuite.

What do we have now?

• lalxxx{-devel}: the C-language package, including shared object libraries, development files, and command-line executables
• python{}-lalxxx: the Python-language package, including SWIG bindings, pure-python/extension modules and command-line scripts
• lalxxx-octave: the Octave-language SWIG bindings

What might be better?

• liblalxxx{-devel}: the C-language library, and development files (headers, pkg-config, etc)
• python{}-lalxxx: the Python SWIG bindings, and pure-python/extension modules
• lalxxx: the command-line scripts from both C and Python languages
• lalxxx-octave: the same Octave-language SWIG bindings

This would leave lalxxx (e.g. lalburst) as the single package needed to bring in the C library, Python bindings, and all command-line executables/scripts. This would enable, for example, switching out the Python library underneath the executables (e.g. from python3-lalxxx to python4-lalxxx) without disturbing the lalxxx package and its dependents.

Who would this impact?

This can be done without any backwards incompatibilities, I think. Specifically:

• users who only want the SWIG bindings don't have to do anything
• users who want the command-line scripts just need to require lalxxx instead of both lalxxx and python-lalxxx
• users who only want the SO library can slowly migrate from lalxxx to liblalxxx (since requiring lalxxx would bring in liblalxxx anyway)

Comments please @adam-mercer, @karl-wette, @jolien-creighton, @ed-maros, @riccardo-sturani, @frank-ohme, @sebastian-khan, @harald.pfeiffer, @maria.haney, @kipp.cannon, @gabriele-vedovato, @marco-drago, @david-keitel, @bfarr, @cjhaster, @john-veitch, @vivien, @salvatore-vitale (all listed CODEOWNERS of subpackages) and @steffen.grunewald, @michael.thomas (packagers)