enhance CONTRIBUTING.md with detailed testing procedures and workflows

exit gracefully if the label doesn't exist and increased verbosity.

3.1.9-rc

skip tests that fail on 'noSuggests' CRAN flavour (#211)

207 missing rhpcblasctl on nosuggest cran flavour (#208)

* conditionally set num threads

* skip this test on CRAN to not overconsume cores when omp_num_threads is not set.

202 skipping re building of vignette outputs due to unavailable depen…

…dencies on nosuggests flavours (#205)

* evaluate chuncks conditional on availability of vignette dependencies. Addressing #202

* conditionally running the benchmarks only if the microbenchmark package is available. Addressing #202.

* Automated Vignette Compilation

* removed Suggests from VignetteDepends

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Co-authored-by: GitHub Vignette Bot <[email protected]>

202 skipping re building of vignette outputs due to unavailable depen…

…dencies on nosuggests flavours (#203)

* evaluate chuncks conditional on availability of vignette dependencies. Addressing #202

* conditionally running the benchmarks only if the microbenchmark package is available. Addressing #202.

* Automated Vignette Compilation

---------

Co-authored-by: GitHub Vignette Bot <[email protected]>

fixed CRAN notes for abn 3.1.4 (#200)

* removed C flag as linking is by C++ runtime libraries

* addressed URL issues from #199

* added `fmesher` to Suggests

* install missing system dependency Abseil for S2, sf and fmesher packages

* removed sudo as most containers run in root

* install missing system dependency Abseil

* Automated Vignette Compilation

* use only C++ linker flags

* removed OPENMP flags from PKG_CFLAGS

* removed `fmesher` as it should be installed with `s2` now.

* removed installation of `abseil` from workflows as this is now done within the containers (furrer-lab/r-containers#53)

* typo

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Co-authored-by: GitHub Vignette Bot <[email protected]>

187 issue with ragg within the installation workflow for windows (#194)

* uncomment the temporary workaround of installing ragg to see if it's not needed anymore

* added gsl path troubleshooting

* print

* use powershell again

* print more environment variables and gsl informations

* test installation without the ragg installation workaround on other platforms

* call cygwin for gsl build flags as gsl-config is a unix thing.

* removed temporal workaround for building `ragg`

* removed temporal workaround for building ragg also on Fedora

Updated citations