related to the namespace bullet point in

• standard library: a roadmap #8450

Description

this was the last module of the standard library with a broken namespace, this PR takes care of this.

• run-tests has been moved to std/mod.nu
• std/testing.nu has been moved to std/assert.nu
• the namespace has been fixed
  • assert is now called main and used in all the other std assert commands
  • for std assert length and std assert str contains, in order not to shadow the built-in length and str contains commands, i've used alias "core ..." = ... to (1) define foo in assert.nu and (2) still use the builtin foo with core foo (replace foo by length or str contains)
  • tests have been fixed accordingly

User-Facing Changes

one can not use

use std "assert equal"

anymore because assert ... is not exported from std.
std assert is now a real module.

Tests + Formatting

• 🟢 toolkit fmt
• 🟢 toolkit clippy
• ⚫ toolkit test
• ⚫ toolkit test stdlib

After Submitting

$nothing

Notes for reviewers

to test this, i think the easiest is to

• run toolkit test stdlib and see all the tests pass
• run cargo run -- -n and try use std assert => are all the commands available in scope?