Add selectable distribution support for cloudera.cluster

[Chaffelson]

Disable dnf AppStream module for Postgresql when centos 8 in use
Set default CM version to 7.4.4 in cloudera.cluster
Ensure that Python2/3 are present on nodes when deploying on Rhel8 family OS
Update utility VM used for download mirror to function correctly with parcel distribution OS
Add default_cluster tag to cluster.yml playbook CM Agent heartbeat test to avoid obscure failures
Enable by setting parcel_distro in definition to [el7, el8, or bionic] per dynamic OS options in cloudera.exe.infrastructure.vars
Change default dynamic inventory selection strings from 'centos7' to match the distribution identity strings of el7 etc. - user can update defaults to a different el7 distro etc. in cloudera.exe.infrastructure.vars
Add Ubuntu 18.04 'bionic' as option to dynamic inventory
Determine preferred parcel distribution in cloudera-deploy init
Add uniqueness to generated dynamic inventory VM name to reflect selection of distribution in case multiple clusters are deployed in the same account
Move dynamic inventory OS selection to globals, update appropriate reference docs to reflect change
Add filtering by distro to download mirror support, and ensure that manifest is still always collected
Enforce no_log always when working with Paywall credentials
Increase initial paywall download timeout to 7200s due to present CDN speed issues when deploying on EC2 outside of us-east-1
Modify ansible.builtin.package lock_timeout to only be used on RedHat, as it is not a Debian option
Pass selected parcel distribution to repo analysis during intial deployment when target cluster OS is not yet determined by deployment
Move cloudera.cluster plays which require knowledge of the cluster distribution to run on the cloudera_manager host instead of the Ansible controller so the correct distribution actions are applied
Fix extract_products_from_manifests filter in cloudera.cluster to correctly reference self and process os_distribution value
Fix import ordering in cloudera.cluster filters.py to not break under recent versions of Python3
Add distribution specific tasks for cloudera.cluster.deployment.repometa so it can identify the cluster distribution using the strings recognised by Cloudera Manager deployment
Force refresh of apt package cache on Debian distributions during OS prereqs setup in cloudera.cluster as the package cache in the image is sometimes missing packages

[tmgstevens]

https://github.com/Chaffelson/cloudera.cluster/blob/debian_fixes/roles/security/tls_signing/tasks/csr_signing_local.yml#L25 - we're going to need to set the executable on that task to /bin/bash as exec 100 > /tmp/ca_server.lock isn't going to run on dash.

[tmgstevens]

Also found that on the ca_server role, on centos 8 you can't install PyOpenSSL using yum, it needs to be via pip, so we're going to need a separate RHEL7/8 codepath there.

Once those changes are in I'm happy to push this

[Chaffelson]

This PR has been updated to also include support for Focal Fossa (Ubuntu 20.04) and handle automatically setting up TLS on deployments 🎉

[tmgstevens]

This looks good to me.
Dan - please could you share what scenarios you have tested, i.e. RHEL7/8, Ubuntu18/20, TLS on/off, etc?

[Chaffelson]

Tested with:
Centos7, Centos8, Ubuntu18.04, Ubuntu20.04
All with tls=True, now that you mention it I probably need to retest without tls

[tmgstevens]

Regression tested with and without TLS against Secure+HA cluster. All looking good.