RCBC-391: SDK Support for Native KV Range Scans

[DemetrisChr]

Added support for KV scans (Prefix, Sampling and Range scans) using the C++ SDK's implementation

Changes

• Core update to use the C++ SDK with the latest range scan implementation
• Added Collection#scan method which uses the C++ SDK to create a range scan orchestrator, starts a scan and returns a scan result iterator
• Added ScanResults class which is the return type of Collection#scan and is an iterator of ScanResult objects. It encapsulates a CoreScanResult object which is created on the C++ side and has a reference to the C++ scan_result object
• Added the Options::Scan class for scan options
• All scan type classes in lib/key_value_scan.rb
• Relevant tests in test/scan_test.rb
• Example code snippet in examples/range_scan.rb

Results

• All tests pass (Tests affected by CXXCBC-345 are skipped for now)
• All FIT tests pass (performer changes in Gerrit change) except the ones requiring the LegacyTranscoder which is not supported by the Ruby SDK at the moment

[cb-sdk-robot]

Can one of the admins verify this patch?