introduce Location type for line/col (maybe also type OneBasedIndex = distinct int for line numbers etc that start at 1)

[timotheecour]

refs nim-lang#17257 (comment)

goal: type safety, self documenting, avoid off by 1 bugs (compiler uses multiple conventions interchangeably which has been source of off by 1 bugs when dealing with line numbers, columns etc)

plausible implementation

• internally represent line numbers as starting from 0
• but when rendering via toLocation, add +1, eg:

template toLocation*(result: var string, file: string | cstring, line: int, col: int) =

# would become:
type OneBasedIndex = distinct int
proc `$`(a: OneBasedIndex): string = $(a.int + 1)
template toLocation*(result: var string, file: string | cstring, line: int | OneBasedIndex, col: int | OneBasedIndex) =