added query pattern extraction on aggregate operation

[PrasannaSM]

Issue 861

Description of changes

Added query pattern extraction on aggregate operation

Testing

Run mloginfo mongo.log --queries whioch contains aggregate operations as well

Result

namespace                  operation    pattern         count    min (ms)    max (ms)    95%-ile (ms)    sum (ms)    mean (ms)    allowDiskUse
test_db.test_coll1         find        {"field1": 1, "field2": 1, "field3": 1, "field4": 1, "field5": 1}          1         470         470           470.0         470        470.0    None
test_db.test_coll2         aggregate         [{"$match": {"field1": 1}}, {"$unwind": 1}, {"$match": {"field2": {"$ne": 1}, "field3": 1, "field4": 1}}, {"$group": {"Count": {"$sum": 1}, "_id": 1}}]         1         252         252           252.0         252        252.0    None

O/S testing:

O/S	Version(s)
macOS	12.2