Adds folding markers for //#region and //#endregion to the json/jsonc
language configuration so that the minimap section headers feature
(editor.minimap.showRegionSectionHeaders) recognizes them and renders
the corresponding section labels.
vscode-json-languageservice already provides folding ranges for these
markers in jsonc, but the minimap section headers contribution reads
folding markers from the language configuration only, which is why the
labels were missing.
Fixes#219561
* add decrease and increase indent patterns for cpp
* adding new line with line comment on next line from within languages that use double slash for line comment