Investigate enabling request body matching in CertificateTests

[pakrym]

Currently there is a part of request that changes every time:

System.InvalidOperationException : Unable to find a record for the request POST https://heathskv.vault.azure.net/certificates//1442592363/import?api-version=7.1-preview
Header differences:
Body differences:
Request and response bodies do not match at index 141:
     request: "gQInrFyDDX+drkCAggAgIIECDizLZe"
     record:  "gQInrFyDDX\u002BdrkCAggAgIIECD"

[pakrym]

cc @heaths

[heaths]

At first glance of the PR, we'll need to ignore certain content which means understanding structure. I wonder if that's something we could instead put into the base matcher as optional behavior. It will probably be common enough.

[heaths]

I don't believe the pay-off here is worth the cost. This has been open a while and the live tests have been run many times since then. If you disagree on the resolution, we can discuss and re-evaluate.