feat: Add provision and deprovision DetailType

[daveroberts-aws]

Issue # (if applicable)

N/A

Reason for this change

There are no DetailType values for provisioning and deprovisioning.

Stack de/provisioning and tenant on/offboarding can be mutually exclusive and we need to accommodate this.

For example, an application stack/cell may be de/provisioned as part of a scaling or migration activity without tenant on/offboarding.

Description of changes

Added PROVISION_REQUEST and DEPROVISION_REQUEST to DetailType and updated EventManager accordingly.

Description of how you validated changes

Normal testing of stack deployment. No changes to tests were required.

Checklist

• [ x ] My code adheres to the CONTRIBUTING GUIDE
• [ x ] I have updated the relevant documentation (if applicable).

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[daveroberts-aws]

I would also raise the topic of standardising the verb-age used in DetailType. Some use the infinitive, ie. PROVISION_, and others use the '-ing' form, ie. ONBOARDING_.

[suhussai]

I would also raise the topic of standardising the verb-age used in DetailType. Some use the infinitive, ie. PROVISION__, and others use the '-ing' form, ie. ONBOARDING__.

+1 to this. This will also be a breaking change, but I think it's important.

[suhussai]

Just a minor point on the extra comment line.