[BUILD] shared libraries with version suffix, along with the symbolic link

[lalitb]

Fixes #2100

Changes

Versioning policy is described here for debian - https://www.debian.org/doc/debian-policy/ch-sharedlibs.html. In general same is followed across other *nix distributions.

• Added CMake option OTELCPP_VERSIONED_LIBS to enable generating versioned shared libs.
• Currently using OPENTELEMETRY_ABI_VERSION_NO as SOVERSION, we can also use MAJOR version. But as per the recommendation, SOVERSION should change for any ABI breaking change.
• The output is as below:

$ ls -ltr /usr/local/lib/libopentelemetry_*common*so*
-rw-r--r-- 1 root root 281640 Apr 20 21:59 /usr/local/lib/libopentelemetry_common.so.1.9.0
lrwxrwxrwx 1 root root     32 Apr 20 22:01 /usr/local/lib/libopentelemetry_common.so.1 -> libopentelemetry_common.so.1.9.0
lrwxrwxrwx 1 root root     28 Apr 20 22:01 /usr/local/lib/libopentelemetry_common.so -> libopentelemetry_common.so.1

$ objdump -p /usr/local/lib/libopentelemetry_common.so.1.9.0 | grep SONAME
  SONAME               libopentelemetry_common.so.1
$

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

Merging #2109 (7f306a8) into main (7ee86a9) will decrease coverage by 0.02%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2109      +/-   ##
==========================================
- Coverage   87.19%   87.17%   -0.02%     
==========================================
  Files         166      166              
  Lines        4784     4784              
==========================================
- Hits         4171     4170       -1     
- Misses        613      614       +1     

see 1 file with indirect coverage changes

[marcalff]

Using OPENTELEMETRY_ABI_VERSION_NO as SOVERSION looks like the correct choice.

See minor comment on dependent options.

[marcalff]

LGTM.

To clarify, I don't think opentelemetry-cpp is ready to use shared libraries yet.

We need to make sure the proper symbol is part of the proper library, see issue #1429.

This is however a different issue, which should not prevent this part to go in the main branch.

Ok to merge.