Refactors generation and usage of CelixTargets cmake files

[pnoltes]

Changes how CelixTargets cmake file are generated and used for installs with multiple build types.

Primary so that there is can be a single CelixTargets.cmake entry point.
Tthis is needed to not break how Celix (or projects export Celix bundles) Config.cmake file works.

I ran into the issue that all project using Celix, exporting bundles and providing a Config.cmake are not building any more.

In the refactored setup, there is always a CelixTargets.cmake file and this file includes all config specific CelixTargets-.cmake files.

Also ensure that multiple imported bundle configs can coexists. When creating a container/docker the correct bundle for the config will be resolved. I tried to mimic as much as possible cmake behavior for imported library targets.

This resolving also make use of CMAKE_MAP_IMPORTED_CONFIG_ and target properties MAP_IMPORTED_CONFIG_ (if present)

I ensured that it will always try to resolve to a imported bundle targets even if no imported bundle target exists for the build type and no MAP_IMPORT_CONFIG exists. If I am not sure how CMake handle this for libraries, but this seems logical for me...

I tested this when installed for the CMAKE_BUILD_TYPE Release, Debug and using the celix-example dir (which can be build standalone).

[codecov-commenter]

Codecov Report

Merging #254 into master will increase coverage by 0.44%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #254      +/-   ##
==========================================
+ Coverage   67.83%   68.27%   +0.44%     
==========================================
  Files         127      127              
  Lines       26375    26894     +519     
==========================================
+ Hits        17891    18363     +472     
- Misses       8484     8531      +47     

Impacted Files	Coverage Δ
...b/pubsub_admin_tcp/src/pubsub_tcp_topic_receiver.c	67.67% <0.00%> (+4.55%)	⬆️
...sub/pubsub_admin_tcp/src/pubsub_tcp_topic_sender.c	69.64% <0.00%> (+5.53%)	⬆️
...s/pubsub/pubsub_admin_tcp/src/pubsub_tcp_handler.c	82.00% <0.00%> (+5.79%)	⬆️

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