Make the keyPattern field in express plan explains more easily parseable

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      The Compass team is working on COMPASS-7794 and ran into some challenges processing the explain output of express plans. In particular, the keyPattern field has a different format for express plans that is proving difficult to parse. For express plans, we see the following output:

                      {
                        "stage" : "EXPRESS_IXSCAN",
                        "keyPattern" : "{ _id: 1 }",
                        ...
                },

      and

                      {
                        "stage" : "EXPRESS_IXSCAN",
                        "keyPattern" : "{ a: 1 }",
                        ...
                },

      whereas regular index scans result in the following:

                                      "stage" : "IXSCAN",
                                "keyPattern" : {
                                        "a" : 1
                                },

       

      The ask is to make the keyPattern field more easily parseable, either by wrapping the field names in quotes:

      "keyPattern": "{ \"a\": 1 }",

      or by serializing the pattern as an object as we do in non-express explain output.

            Assignee:
            Andrei-Cristian Murică
            Reporter:
            Hana Pearlman (Inactive)
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              Created:
              Updated:
              Resolved: