GH-1066/GH-1072 - Support use of META() in N1QLQueryCreator and changed QueryCriteria to use N1QLExpression as key

[mmonti]

This commit fixes the generated query by N1QLQueryCreator when the criteria includes an id or a version property, adding a META($bucket) function

It also removes the need of maybeBacktics() in QueryCriteria defining N1QLExpression as key instead of String.
Public methods where(), and() and or() with String key delegate to the same with N1QLExpression as argument.

Related tickets:

• findById...AndXXX method derived query generates wrong statement #1072
• QueryCriteria.where() adds backticks to ALL keys, breaks keys that use META()  #1066

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