Test, validate and match regular expressions
Parses TypeScript-style interface documentation entries (e.g., VSCode's DecorationRenderOptions), matching two-space-indented property lines like 'propertyName?: type' followed by a deeper-indented description line. Named capture groups (indent, prop, delim, type, descMargin, descIndent, desc) make it easy to extract each field. Uses PCRE extended mode (?x) for readability with global and multiline flags to process many entries in a document.