feat!: use composition and inheritance to build service managers

[NucciTheBoss]

This pull request enhances the API of slurm_ops to use composition and inheritance to build the Slurm service operations managers. This makes it easier for us to construct managers around slurmctld, slurmd, slurmdbd, and slurmrestd and share logic for configuration and service management between them.

Some use cases

bulk update the configuration of slurmctld:

from charms.hpc_libs.v0.slurm_ops import SlurmManagerBase, ServiceType

slurmctld = SlurmManagerBase(ServiceType.SLURMCTLD)
slurmctld.config.set({"option1": "value1", "option2": "value2"})

set a new munge key:

from charms.hpc_libs.v0.slurm_ops import SlurmManagerBase, ServiceType

slurmd = SlurmManagerBase(ServiceType.SLURMD)
slurmd.munge.set_key("encodedmungekey")
slurmd.munge.restart()

start slurmrestd:

from charms.hpc_libs.v0.slurm_ops import SlurmManagerBase, ServiceType

slurmrestd = SlurmManagerBase(ServiceType.SLURMRESTD)
slurmrestd.enable()

add additional, charm-specific functionality:

from charms.hpc_libs.v0.slurm_ops import SlurmManagerBase, ServiceType

class SlurmctldManager(SlurmManagerBase)

    def __init__(self) -> None:
        super().__init__(ServiceType.SLURMCTLD)

        # Compose additional manager functionality.
        self.cgroup = ...

Misc.

Adds kebabizer from @jedel1043. The function format_key(...) will be used to format Slurm configuration keys before passing off to the Slurm configuration editor.

[jedel1043]

Looks great! I just have some questions around needing Pyfakefs.

[NucciTheBoss]

@jedel1043 good catch with pyfakefs! Ready for review again 🔎

[NucciTheBoss]

Also, for future reference before we merge, we need to bump the lib patch version so that the updated lib will get published to Charmhub

[jedel1043]

LGTM!