Gnu Coreutils - uucoreutils ls fix

[alexkunde]

Hi,
this crate is used via lscolors crate in the rust drop-in replacement for gnu coreutils called uucoreutils.
The original GNU util ls is still using some extended modes that are not supported by this crate.

1. two-digit style codes -> Add feature: gnu_legacy mode for ansi styles #39
2. reset prefix for any string -> Add resetted styling #40

To continue using this crate, it would really help to improve on those two topics. The added PRs will add both functionalities.
Both are using main branch, so I guess the second merge would need a rebase first.

After the merge, this GNU test will turn green:

OLD

FAIL: tests/ls/color-term
=========================

--- exp 2023-05-16 15:56:30.337121900 +0200
+++ out 2023-05-16 15:56:30.102644900 +0200
@@ -1,4 +1,4 @@
-^[[0m^[[01;32mexe^[[0m$
-^[[0m^[[01;32mexe^[[0m$
+^[[1;32mexe^[[0m$
+^[[1;32mexe^[[0m$
 exe$
 exe$
FAIL tests/ls/color-term.sh (exit status: 1)

After both PRs

SUCCESS: tests/ls/color-term
=========================
@@ -1,4 +1,4 @@
^[[0m^[[01;32mexe^[[0m$
^[[0m^[[01;32mexe^[[0m$
 exe$
 exe$
FAIL tests/ls/color-term.sh (exit status: 1)

Thanks for your help!

[alexkunde]

Both features have been added.