(MAINT) Mergeback from 0.4.1 release

(MAINT) Ensure tag task actually tags with version

…-guidance

(MAINT) Add build & release steps to readme

…r-testing

(MAINT) Add appveyor testing

This makes the log much more manageable without a long list of
pending examples.

This likely is a problem with the tests not reacting well to a
behavioral change in powershell 7, and not a code issue. The same
tests ran fine previously with 6.2.4-1.ubuntu.18.04 in
https://travis-ci.com/github/puppetlabs/ruby-pwsh/jobs/293023278
while the same commit (03e90c7) fails on powershell 7.

This behaviour is also linux-specific.

(IAC-859) Add ruby 2.7 to test matrix

Prior to this commit the code for the base provider of the new
puppetized DSC modules was vendored into each module; this
meant that if the provider ever needs to be updated, *every*
prior release of the puppetized module would need to be built
again and pushed with an incremented number.

Moving the base provider to the pwshlib Puppet module (which
is this ruby library packaged as a Puppet module) means that
the provider can be updated separately from the PowerShell
builder code and does not require rebuilding puppetized modules,
only updating the reference pin for pwshlib.

This also makes testing the provider easier as it lives in a
ruby library now instead of in a PowerShell module.

…sc-provider

(IAC-1045) Add the DSC base Puppet provider to pwshlib

(MAINT) Prep for 0.5.0 release