RFC: Import Style Borrowing

[beef331]

Borrows are module level operations that should be easy. Making them easier involves a way to quickly and easily select a module a procedure name and whether to export them
Consider the following:

type NotString = distinct string
from system borrow add # Borrows all `add` from system and does not export them
import std/strutils
from strutils borrow contains* for NotString
proc contains(s: string, chars: set[char]): bool {.borrow.} 
# The above replaces the exported with an unexported contains,
# leaving the `contains(s, sub: string): bool` variant exported

Rules for this borrowing:

• The old borrow syntax can still be used, but is preferred to use just for overridding export level (Still looking for a better way)
• Module must be included in borrowing
• Multiple borrows can happen at once
  borrow from strutils contains, capitalizeAscii for NotString
borrow strutils.contains, system.add for NotString
• Export marker can be applied to export all borrows from a statement