Refactor Analysis Report Testing Code

[popescu-v]

Description

Currently, analysis report objects build an internal CSV-like format, which is very useful for testing purposes. However, on each analysis report evolution, this internal format needs to be maintained and kept in sync with Khiops' own CSV (Excel) report format.

The goal of this issue is several-fold:

• eliminate the internal CSV format
• endow AnalysisResults and CoclusteringResults objects with a JSON serialization capability, resulting in JSON files which are compatible with the Khiops-generated reports.
• refactor the testing "framework" to operate on JSON reports rather than on the CSV reports, as of now.
• update the test references to use JSON reports instead of CSV reports.

Questions/Ideas

• To fully generate JSON reports, we need to find the attach node for each report "unit"; this is unlike the CSV reports, whose units have the ability to serialize themselves on a "local" (that is, context-free) basis.
• Path differences need to be handled, between Windows and UNIX.

[popescu-v]

Done in PR #403.