Enable Manylinux wheel builds

[sc1f]

This PR makes Perspective's linux wheels fully Manylinux2010 and Manylinux2014 compatible, adds wheel build tasks for MacOS 10.14 (Mojave) and MacOS 10.15 (Catalina), as well as ensures passage of the conda-forge Mac build.

Changelog

• Edits dockerfiles to include PyArrow from source, as well as force an install of auditwheel
• Fixes CMakeLists to allow full Manylinux builds to pass due to a difference between PYTHON_INCLUDE_DIRS and Python_INCLUDE_DIRS.
• Runs auditwheel show and auditwheel repair whenever Linux wheels are built, which ensures that all wheels are fully portable and compliant to the Manylinux PEPs.
• Adds a Python 2 wheel task for Manylinux2010
• Adds Azure pipelines tasks for MacOS wheel builds similar to Manylinux builds
• Adds a MacOS 10.15 Azure pipeline
• Removes CLOCK_MONOTONIC from compat_impl_osx, which is breaking builds on conda-forge. This is due to clock_gettime and CLOCK_MONOTONIC not being implemented in MacOS until 10.12. Because the method that calls clock_gettime is not used anywhere in the compiled code, I commented out the original implementation and forced the offending method to return a 0.

[timkpaine]

updates:

• filter down the number of required builds for non-release builds
• remove "official"
• default to manylinux2010
• consolidate all python versions into 2 docker images, manylinux2010 and manylinux2014

[wesm]

Do you all plan to get yourselves synced up with pyarrow mainline?

[sc1f]

@texodus this should be good to go

[sc1f]

@wesm the custom arrow build we have for Emscripten might take a little fixing, but it shouldn't be too hard to get Perspective on 0.17 in the near future

[texodus]

Looks good! Reviewed copiously offline.