Fix handling ORDER BY part of queries

Summary:

• new APIs
• maintain relations between connections, queries and column infos
• fix cloning queries with ORDER BY
• update and add autotests

FIXED-IN:3.2
BUG:392753
CCBUG:393705

Test Plan:
Required: KEXI & KDb 3.2 (current master)

Test 1: Open report and query from https://bugs.kde.org/show_bug.cgi?id=392753#c0 in design and data views.
Expected: works, no crashes

Test 2: Try these on a standard Persons and Cars test:
select id from cars order by owner;
select id from cars order by owner, model, id;
select id, model from cars order by 2, 1;

Expected: works, no crash

Reviewers: piggz

Reviewed By: piggz

Subscribers: Kexi-Devel-list

Tags: KDb

Differential Revision: https://phabricator.kde.org/D12873