Fixes for query designers and query data view (logic, memory and stability fixes)

Summary:
(Thanks to the ASAN project for helping with many of these fixes)

1. Synchronize the "dirty" flag between Design and Text views

For now only used by Query Designer

2. GIT_SILENT Make *ownedByWindow required (simplify code), update docs

3. SQL designer: remove possible memory leak if the parsed query object is still present on destruction

4. Queries: fix possible crash in data view when the query design changes in a design view

Before replacing old query schema by a new one unassign the old from the data view.

5. Queries: after parsing the SQL only assume the query changed if the SQL differs from the previous SQL

This reduces number of refreshes in Design and Data view.

Test Plan:
Please also apply D9410 to KDb and test with it.

Play with all 3 query views for trivial and non-trivial queries.
Including tables having lookup fields is recommended too.

Reviewers: piggz

Tags: KEXI

Differential Revision: https://phabricator.kde.org/D9409

FIXED-IN:3.1.0