Enable setting a Toggling Lock on an Activity Directive to prevent it from being moved

[cchouina]

Checked for duplicates

Yes - I've already checked

Alternatives considered

Yes - and alternatives don't suffice

Related problems

This issue may be related (I see mention of Read/Write) :
#1364

Describe the feature request

For (read-only) External Events that I need to represent in Aerie, I would like to be able to represent them as Activities instead of Resources to get access to more Scheduling Goal constructs based off of them, but currently, Activity Directives are always editable. I would like to be able to lock the Activity Directives to their scheduled times, and disallow editing, unless I toggle off the "locked/read only" protection. If a new type called an Event were created that mimics Activity Directives, except for its permissions, that would also work. An Event feature request is in-line with the latest CCSDS MPS Draft: https://cwe.ccsds.org/moims/docs/Forms/AllItems.aspx?RootFolder=%2Fmoims%2Fdocs%2FMOIMS%2DMP&View=%7B72CC1C3E%2DEFA9%2D498B%2DBEA5%2DC88E7DEE0C54%7D&

[cchouina]

https://cwe.ccsds.org/moims/default.aspx#_MOIMS-MP