Feature/579 automatic dependency deduction

[PengZheng]

This PR fixes #579 by implementing automatic dependency deduction among components within the Celix package.

Now we can specify only what we need, and a minimal Conan package with corresponding feature (and its internal dependencies, but nothing more) will be built for us automatically.

For example, if we only need PushStreams, the following snippet should be enough for any downstream project:

            self.requires("celix/2.3.0")
            self.options['celix'].build_pushstreams = True

Or we can create a minimal Conan package with only PushStreams and Promises support by the following command line:

conan create . -b missing -o celix:build_pushstreams=True

To this end:

• All build_ options default to be False. Please note that CMake caches' defaults are not changed.
• Error injectors for Celix components are under the control of corresponding build_ option. This is necessary to fix https://github.com/apache/celix/actions/runs/5560191654/jobs/10156995210 CodeCoverage.cmake has been updated to exclude them from Coverage statistics.
• An Celix::celix dummy target is introduced. Now all components can be turned off, which will result in empty package. Without this target, install(TARGETS ...) will report unknown export "celix" error. Note that creating an empty package is the fastest way of publishing a new conan package (without actually building anything). In my day job, I normally publish package this way (CI has already guaranteed that the package can be built correctly).
• A GitHub work flow is introduced to try to create various Conan packages with only one build_ option enabled.
• etcdlib and promises can still be built the old way. Though building with Conan is my preferred way.
• conan_test_package has been updated to discard usage of deprecated headers, and more tests are added.

Documentation has not been updated to reflect the above. We may need more usage experience.

@xuzhenbao I noticed if mdnsresponder/1790.80.10 were used, tests failed. Is that normal?

[codecov-commenter]

Codecov Report

Merging #589 (e492c63) into master (8bcac0f) will increase coverage by 0.03%.
The diff coverage is 100.00%.

❗ Current head e492c63 differs from pull request most recent head c789b89. Consider uploading reports for the commit c789b89 to get more accurate results

@@            Coverage Diff             @@
##           master     #589      +/-   ##
==========================================
+ Coverage   78.50%   78.54%   +0.03%     
==========================================
  Files         234      234              
  Lines       35389    35431      +42     
==========================================
+ Hits        27782    27829      +47     
+ Misses       7607     7602       -5     

Files Changed	Coverage Δ
libs/framework/src/celix_launcher.c	92.35% <100.00%> (ø)

... and 4 files with indirect coverage changes

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[pnoltes]

I assume this will generate a imported target?

[PengZheng]

Yes, this only serves to define the Celix export.

[pnoltes]

Does this mean that the celix cmake function celix_subproject is no longer used to configure dependecies, but this is now done using the Conanfile?

So for pushstream the lines :

        if self.options.build_pushstreams:
            self.options.build_promises = True

[PengZheng]

Yes. Previously celix_subproject will only hint our users to enable missing components without automatic configuration.
For a long chain of dependencies, users have to try several times to work out a working configuration for Celix.
Imagine that we have several Conan packages, each of them has intra-package dependencies like Celix, and they also have inter-package dependencies. Then working out a working configuration for a downstream user can be daunting.
With this in place, our users only specify what they need directly, everything else is automatically configured like charm.