Missing borrow annotations in `Std.Internal.UV.System`

Prerequisites

Please put an X between the brackets as you perform the following steps:

• Check that your issue is not already filed:
  https://github.com/leanprover/lean4/issues
• Reduce the issue to a minimal, self-contained, reproducible test case.
  Avoid dependencies to Mathlib or Batteries.
• Test your test case against the latest nightly release, for example on
  https://live.lean-lang.org/#project=lean-nightly
  (You can also use the settings there to switch to “Lean nightly”)

Description

In https://github.com/leanprover/lean4/blob/30ceb3260d7d7536092fedff969b4b2e8de7f942/src/Std/Internal/UV/System.lean, there are several functions that accept a String argument which is received as a b_obj_arg in the runtime, but which are missing the borrow annotation.

Impact

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Start in src/Std/Internal/UV/System.lean and inspect the functions accepting String arguments that are received as b_obj_arg in the runtime. Confirm the missing borrow annotations and validate the change with the issue's minimal, self-contained test case against the latest Lean nightly.