feat: extending maintenance allowance through API

[theautoroboto]

• Identified the issue which this PR solves.
• Read the CONTRIBUTING document.
• Code builds clean without any errors or warnings.
• Added appropriate tests for any new functionality.
• All new and existing tests passed.
• Added comments in the code, where necessary.
• Ran make check to catch common errors. Fixed any that came up.

Description:
Extending maximum maintenance mode from 8 hours to 24 hours. We also want to allow a 5 minute grace period for clock drift.

Which issue(s) this PR fixes:
N/A

Out of Scope:
N/A

Screenshots:
N/A

Describe any introduced user-facing changes:
N/A

Describe any introduced API changes:
Nothing new introduced, but this does alter the maximum amount of time a service can be added to maintenance mode

Additional Info:
none

[Forfold]

LGTM,

though the comment above the function looks wrong- probably a copy paste. If you don't mind could you update it to something like

// Normalize will validate and 'normalize' the Service -- such as setting the minimum duration to 0.

[Forfold]

thanks! 🎉