Docs for SERVER-33844: Change Streams - provide details for metadata operations instead of (or in addition to) invalidation

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Original Description

Description:

Marking this as docs needed, however it would be easier to address each ticket in the epic.

Engineering Ticket Description:

When watching a database or entire cluster, provide notification of metadata events like collection drops and renames rather than invalidating the stream. In case of watching a single collection, use the same format to provide details about invalidation (whether it was caused by collection drop, db drop, collection rename, etc).

Original Description:

Change streams report the namespace for operations such as inserts, updates and deletes. The namespace information would be useful in case of the invalidate event.

Here is an example where the namespace would be extremely helpful:

mdbsrv-01
db1.coll1
db1.coll2
db1.coll3

Application thread-1 opens a change stream on db1.coll1 and thread-2 opens a change stream on db1.coll3. Everything captured from these collections will be send to mdbsrv-02, db2.do_it_now.

If db1.coll1 gets dropped, the invalidate event is triggered and a invalidate document is inserted into mdbsrv-02, db2.do_it_now. The invalidate document only contains the _id and operationType: "invalidate".

By looking into db2.do_it_now, how do I know which collection has inserted the invalidate document into the collection?

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Description

Scope of changes (files that need work and how much)

Impact to other docs outside of this product

MVP (work and date?)

Resources (e.g. Scope Docs, Invision)