[KubaO]

Adds Common Errors sections for the FileSystem module, the Collection and ErrObject classes, VBA Financial, HiddenModule, Compilation and TbExpressionService. It also adds a Literal Keywords page and makes impexp refuse an argument that holds a double quote.

• Run-time errors: batches 7 to 10. Each has its data under errors/, a Common Errors section on each page, and its findings in WIP.Errors.md. The owner's rulings are applied. The expression service's other differences stay NOTEs. expression-service-error-numbers now asks only for errors to pass through unchanged.
• Literal Keywords: a new page with a section each for Nothing, Null, Empty, True and False, indexed as keywords at their headings. check_symbol_index now refuses a non-string symbols: entry.
• impexp: refuses an argument holding a double quote (a quoted folder ending in a backslash) and prints the command meant, in all three editions. The page's examples drop the trailing backslash. --self-test passes 21/21, and parity passes 25/25 with IMPEXP_EXE.
• Defects queued: about 120 files under bugs/, entries and reproducers. Examples:
  • Batch 7: kill-hidden-system-files, filecopy-error-numbers, filesystem-argument-checks; file-errors-unspecified is extended.
  • Batch 8: collection-index-checks, err-raise-hresult-mapping, err-helpfile-helpcontext-codegen.
  • Batch 10: the vbaCastObj missing 13.
  • Literal Keywords: nothing-let-compiles, nothing-let-variant-no-error.