Issue 13689: byCodeUnit fails to be a random access range.

Add static assert to ensure random accessability.
std.format: clean imports

remove new private stuff

add local import

add local import

remove global std.con import
std.utf: clean imports
std.encoding: clean imports
Add `@nogc` attribute
Merge pull request #2674 from sinkuu/uni

Mark some functions in std.uni as `@nogc`
Merge pull request #2670 from 9il/encode

std.encoding: clean imports
Merge pull request #2669 from 9il/utf

std.utf: clean imports
Remove private staticFilter from AutoImplement and use std.typetuple.Filter instead
std.uni: clean imports
std.uuid: clean imports
std.digest.*: clean imports
std.bitmanip: clean imports

revert some changes
Merge pull request #2671 from 9il/uni

std.uni: clean imports
Merge pull request #2678 from 9il/uuid

std.uuid: clean imports
Merge pull request #2680 from 9il/bm

std.bitmanip: clean imports
Merge pull request #2679 from 9il/digest

std.digest.*: clean imports
Merge pull request #2676 from Geod24/cleanup-autoimplement

Remove private staticFilter from AutoImplement and use std.typetuple.Filter instead
Merge pull request #2666 from 9il/format

std.format: clean imports
Merge pull request #2656 from quickfur/issue13689

[trivial] Issue 13689: byCodeUnit fails to be a random access range.