Multiview request changes to support Couch3

[ricellis]

Checklist

• Tick to sign-off your agreement to the Developer Certificate of Origin (DCO) 1.1
• Added tests for code changes or test/build only changes
• Updated the change log file (CHANGES.md|CHANGELOG.md) or test/build only changes
• Completed the PR template below:

Description

Updated view multi-query to work with CouchDB 3

For PRs without an associated issue and/or test/build issues

1. Steps to reproduce and the simplest code sample possible to demonstrate the issue

Run com.cloudant.tests.ViewsTest#multiRequest against CouchDB 3.

2. What you expected to happen

Test to pass.

3. What actually happened

Test fails because POST to {db}/_design/{ddoc}/_view/{viewname} with queries was deprecated since CouchDB 2.2 and is removed in CouchDB 3.

Approach

Replace POST of { "queries": [...]} body to {db}/_design/{ddoc}/_view/{viewname} with POST to {db}/_design/{ddoc}/_view/{viewname}/queries.
On badmatch failure fallback to original POST to maintain compatibility with CouchDB versions < 2.2.

Schema & API Changes

• "No change"

Security and Privacy

• "No change"

Testing

• No new tests because existing tests cover this functionality and test matrix ensures coverage of new and old endpoints.

Monitoring and Logging

• "No change"