move format to std.format

The reason is to do not import `std.uni` tables, `std.string` and
probably `std.algorithm`. Note that format is used in CTFE code and
`Exception` handing.

 And it is more comfortable to import `format` from `std.format`.

std.format: clean imports (2)

remove import std.math : pow from std.uni

update scope imports in std.algorithm

update scope imports in std.exception

doFormat -> template

update scope imports in std.typecons

update scope imports in std.functional

update scope imports in std.range

update std.conv scope import

std.format: clean imports (2)

remove import std.math : pow from std.uni

update scope imports in std.algorithm

update scope imports in std.exception

doFormat -> template

update scope imports in std.typecons

update scope imports in std.functional

update scope imports in std.range

move sfromat

add public import of sformat