NH-89406: improve control for building debug version of the extension and added documentation

[xuan-cao-swi]

Description

1. remove debug flag to reduce the size of apm
2. add instruction for debugging with core dump file
3. add extconf_test.rb to test the workflow of extconf (makefile construction) if OBOE_DEBUG, OBOE_DEV, OBOE_STAGING appears. The test case require deep stub on each different function to avoid c lib dependency.
4. OBOE_DEBUG will make the fetch of production release with relwithdebug directly.

Test (if applicable)

[cheempz]

Thanks @xuan-cao-swi! This is really great info, much appreciated. I left a bunch of comments based on understanding below (which may be wrong):

• in order to get extended info out of coredump, the crash needs to be reproduced using special version of solarwinds_apm
• this special version can be achieved purely at install time by setting env var OBOE_DEBUG which enables more info in the c-extension binding code AND uses a version of liboboe that comes with extended debug info.

[cheempz]

nice DRYing :)

[xuan-cao-swi]

in order to get extended info out of coredump, the crash needs to be reproduced using special version of solarwinds_apm

For now yes, here is the difference log info

# without .debug symbol file
#5  0x0000ffff92c1fd04 in oboe_ssl_reporter::eventSender() () from /root/.rbenv/versions/3.1.0/lib/ruby/gems/3.1.0/gems/solarwinds_apm-6.0.6/lib/../ext/oboe_metal/lib/liboboe.so

# with .debug symbol file
#5  0x0000ffff9841c6ac in oboe_ssl_reporter::eventSender (this=0xffff9927c010) at /__w/solarwinds-apm-liboboe/solarwinds-apm-liboboe/liboboe/reporter/ssl.cpp:1677

# with ReleaseAndDebug and .debug file
#5  0x0000ffff9841c6ac in oboe_ssl_reporter::eventSender (this=0xffff9927c010) at /__w/solarwinds-apm-liboboe/solarwinds-apm-liboboe/liboboe/reporter/ssl.cpp:1677
    ptr2 = 0x0
        grpcRequest = {< ...

this special version can be achieved purely at install time by setting env var OBOE_DEBUG which enables more info in the c-extension binding code AND uses a version of liboboe that comes with extended debug info.

Yes, and also need the liboboe build with ReleaseAndDebug

[cheempz]

LGTM! really appreciate the revisits and added tests @xuan-cao-swi. We'll need to bump the liboboe version to 15.0.2 for debug install to work, but feel free to put that in as part of the main release prep.