feat(sql-workspace): caret at the error position, one error panel for SQL and Mongo (#1557)

[ZhuchkaTriplesix]

Closes #1557 (the parts #1701 left: items 3 and 4)

3. The caret goes to the error. When one statement fails and the driver says where, the editor's caret moves to that place in the user's own text:

• SQLite gives Causing statement (at position N), a byte offset into the statement it prepared, which is the app's SELECT * FROM (\n<sql>\n) wrapper (fix(sqlite): columns with the same name collapse into one in query results #1144); the wrapper's 16 characters are taken off and the bytes turned into characters (a é before the error does not shift it).
• PostgreSQL gives ServerException.position (1-based, characters); the row limit the app appends comes after the text, so nothing shifts.
• MySQL gives none; the caret stays where it was.
• Leading blank lines of the run text and the statement's start inside a selection or script are counted, and the caret is clamped if the text was edited during the run. Failures in a multi-statement run already moved the caret to the failed statement.
  QueryErrorText.offsetIn(error, sql) does the mapping; offsetOfPgPosition is its PostgreSQL half, separate because ServerException cannot be built in a test.

4. One error panel. The headline / Show details / Copy error panel moved from ResultsTab into QueryErrorView (shared/widgets). ResultsTab uses it as before, and the Mongo query workspace now shows its Query Error through it too (an inline variant for the box it sits in): the driver message as the headline, the rest folded, and Copy.

Not done: a squiggle under the error. The caret and the selection do the job of finding it; an underline needs a decoration layer in the editor, which is its own change.

Tests: query_error_text_test (SQLite with and without the wrapper, bytes vs characters, outside the text, MySQL, PostgreSQL positions), generic_sql_workspace_error_caret_test (the caret lands on the column, blank lines are counted, no position leaves the caret), query_error_view_test (headline, details, copy, inline, reset on a new error). The existing results-tab and Mongo query tests pass unchanged; workspace, mongodb, database and shared tests pass locally (1464).