fix: apply host updates and convert the host_tags list

[nagaboinaramgopal]

Description

Two problems with the cloudstack_host resource.

resourceCloudStackHostUpdate built its UpdateHostParams and set allocation_state and host_tags on it, but never called UpdateHost, so updating either field silently did nothing.

host_tags is a schema.TypeList, so the SDK returns []interface{}, but both create and update asserted host_tags.([]string), which panics with interface conversion: interface {} is []interface {}, not []string when host_tags is set. Neither field is ForceNew, so the update path is reachable.

Fixed by calling UpdateHost when a tracked field actually changed, and by converting the list to []string on both the create and update paths.

Testing

Two unit tests, no live CloudStack:

go test ./cloudstack/ -run 'TestHostCreateHostTagsDoesNotPanic|TestHostUpdateCallsUpdateHost'

TestHostCreateHostTagsDoesNotPanic creates a host with host_tags set; it panics against the current code and gets past the conversion with the fix. TestHostUpdateCallsUpdateHost runs an update with a changed field and asserts the returned error comes from the UpdateHost request; without the fix the update never calls UpdateHost and falls through to the read, so the test fails.