[Proposal] Random Unification

Update implementation link

Update current example

Correctly gets a number within the bounds

Fixes some typos

Update implementation text

Update proposal to match mailing list discussions

Use `SecRandomCopyBytes` for older macOS versions

Update to reflect mailing list

Rename pick to sampling

Clarify a lot of discussions

Use focus instead of scope

Final remark for T.random

Fix some typos

Prefer UInt over UInt64

Comment more on design

Alternative on Collection.random

Use code blocks for Collection.random

Missed some code

Last change to T.random

Author: Azoy