DBA: language selection and result-view improvements

[GuntherRademacher]

This is a follow-up to the CodeMirror 6 editor in the DBA.

Editor

• language follows the file extension: XQuery (default and .xq*), XML, JSON, otherwise plain text
• no syntax-error marker on an empty editor

Result view (read-only)

• highlighting follows the result content (XML / JSON / text)
• code folding

Bundle

• rebuilt static/cm6.js: adds JSON and a runtime language switch
• refreshed XQuery function signatures and documentation links
• backward-compatible

The read-only Jobs result viewer gains the same folding, other pages are unchanged.

[ChristianGruen]

I’m afraid this one will need to be rebased, if possible at all: js.js has been split into many single files, and there is one central place now where xquery suffixes are checked.

[GuntherRademacher]

Merged branch 'main' into 'cm6', adapting editor/result language selection to the restructured DBA ('files.js').