[#1009] Joint test client for inference and query evolution

[andre-senna]

This is a new test client for inference and query evolution. The idea is to have a simplified inference algorithm which uses query evolution to evolve a chain of links in order to prove a premise.

This client is supposed to be used to solve both Rejuve-Flybase and Toy inference problem. To use it in the later, it's still required to fix some of the queries (e.g. for context creation).

Minor fixes e.g. in the Query Engine have also been added in order to make the client work. These are listed below.

• ContextBroker: added a new proxy parameter DISREGARD_IMPORTANCE_FLAG which is passed to the query engine in order to define if STI is supposed to be used or not in the query.
• QueryEvolutionProcessor: fixed the way correlation query elements are replaced by query answer elements. The previous code was made fine-tuned to the word toy problem and were not generic. The way it is in this PR, this code is (hopefully) general enough to be used in any problem.
• LinkSchema: added a new constructor parameter which is a flag to optionally disregard STI when fetching query answers
• LinkSchema: added a logic to determine if the LinkTemplate is a "flat" pattern (i.e. has no nested link templates). This is just a preparation to a code that will be made in a follow-up PR which will use this information in order to avoid fetching data from MongoDB when the pattern is flat.
• LinkSchema: added a INFO log message to show progress on processing of long queries.
• MettaParserActions, PatternMatcherQuery*: support for this new disregard_importance flag
• Multiple tests have also been updated because of this change in LinkTemplate constructor

[ccgsnet]

LGTM