Convert user tasks and user login state to new cache collections

[rosstimothy]

Moves the resources to the new cache collection scheme that was introduced in #52210. No additional functionality changes have been made here. This should be a purely mechanical translation to the new internal caching machinery.

[zmb3]

Does StrictObjectToStruct export a pointer to a pointer?

[rosstimothy]

I shamelessly copied this from access lists. It looks like all existing variants of this resource style use the same pattern though. So if it's not correct we need to fix it everywhere.

teleport/api/types/accesslist/accesslist.go

Lines 410 to 414 in a15a952

	func (a *AccessList) CloneResource() types.ResourceWithLabels {
	var copy *AccessList
	utils.StrictObjectToStruct(a, &copy)
	return copy
	}

teleport/api/types/discoveryconfig/discoveryconfig.go

Lines 181 to 185 in a15a952

	func (a *DiscoveryConfig) CloneResource() types.ResourceWithLabels {
	var copy *DiscoveryConfig
	utils.StrictObjectToStruct(a, &copy)
	return copy
	}

teleport/api/types/externalauditstorage/externalauditstorage.go

Lines 238 to 242 in a15a952

	func (a *ExternalAuditStorage) Clone() *ExternalAuditStorage {
	var copy *ExternalAuditStorage
	utils.StrictObjectToStruct(a, &copy)
	return copy
	}

[zmb3]

Looks like we just pass it to (json.Decoder).Decode so we really don't need the double pointer, though it will work just fine.

[espadolini]

If we changed this to

	var copy UserLoginState
	utils.StrictObjectToStruct(u, &copy)
	return &copy

then ((*UserLoginState)(nil)).Clone() will be equivalent to &UserLoginState{}, right now it returns (*UserLoginState)(nil).

Obviously neither option is in any way sane and we should write or derive some clone function - and awalterschulze/goderive keeps distinguishing itself in making the entirely wrong choices once again, since it will unconditionally use unsafe and reflect to clone private fields of types which is absolutely wild - but in the meantime the way StrictObjectToStruct is being used is the least worst way.