Remote playbooks in prepare; Common attributes extended; Nested root warning

Main improvements and fixes:

• Error out if reboot timeout is exceeded
• Initialize workdir thread-safe
• Add support for remote playbooks in prepare
• Print escaped command suitable for manual debugging
• Less eager to disable nitrate case during export
• Move tag and tier to common core attributes
• Hint user if 'tmt init' creates nested root

Whole change log:

• Unify Polarion case searching
• Error out if reboot timeout is exceeded
• Initialize workdir thread-safe
• Add support for remote playbooks in prepare
• Add plan schema for errata and minute plugins
• Correct rhts command names in stories file
• Print escaped command suitable for manual debugging
• Fix report plugin not getting arguments from fmf file
• Less eager to disable nitrate case during export
• Move tag and tier to common core attributes
• Use /bin/bash instead of /bin/sh for execute
• Reorder step and their base plugin classes
• Fix prepare/multihost docs to match implementation
• Teach schema validation tests to peek into other trees
• Clarify motivation for creating id during export
• Add link-polarion option and fix link searching bug
• Ignore race in last-run symlink creation
• Fix polarion tcmscaseid search
• Force order of clean operations
• Convert status/clean argument to option
• Report enabled plans/tests/stories via option
• Hint user if 'tmt init' creates nested root
• Require libvirt-daemon-config-network as well
• Add type annotation for /steps/prepare/install.py
• Encapsulate created file within script's dataclass
• Adds normalization layer to base classes based on fmf
• Fixes data class used for local guest creation
• Fixes Artemis guest data class link
• Making tests/full more usable
• Add typing for tmt/steps/provision/podman.py
• Add typing for tmt/steps/provision/testcloud.py
• Add typing for tmt/steps/provision/local.py
• Remove unused keys parameter from wake() methods
• Adds types describing tmt constructs when as stored in raw fmf data
• Typing /steps/provision/connect.py
• Allow raising an exception on validation errors
• Inject logger object to base node classes inheritance
• Fixes use of SSH keys in testcloud and connect plugins
• Annotate tmt.steps.provision
• Ask mypy to show error codes in its messages
• Testcloud expects disk and memory to be int
• Do not inherit classes from object
• Use keyword-only init in base fmf-backed classes
• Use decorator to register plugin methods
• Demonstrate inheritance on a virtual test example
• Add a simple hint how to write user messages
• Add typing for steps/finish/ansible.py
• Remove unneeded parameters for step load/save (#1428)
• Normalize step data to be always stored a list internally
• Display test/plan/story name in parametrized schema tests
• Allow numbers and booleans to be values of environment
• Give a reasonable error for old data format
• Add typing for tmt/steps/finish/init.py
• add typing for steps/discover/shell.py
• Adds a fmf node validation layer to core classes (Test/Plan/Story)
• Add missing keys role and where to schemas
• Extend plan schema with all known step plugin schemas
• Correcting rhts aliases & adding rhts opt.
• Adds a generic "wait for condition" primitive
• Disallow push/pull/execute if guest is unavailable
• Rename "default how" step attribute to enhance its visibility
• Use textwrap.dedent() to unindent docstrings