sort/ls: implement version cmp matching GNU spec

This reimplements version_cmp, which is used in sort and ls to sort
according to versions.
However, it is not bug-for-bug identical with GNU's implementation.
I reported a bug with GNU here:
https://lists.gnu.org/archive/html/bug-coreutils/2021-06/msg00045.html
This implementation does not contain the bugs regarding the handling of
file extensions and null bytes.

Cargo.lock

@@ -1434,21 +1434,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
-[[package]]
-name = "semver"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
-dependencies = [
- "semver-parser",
-]
-
-[[package]]
-name = "semver-parser"
-version = "0.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
-
 [[package]]
 name = "sha1"
 version = "0.6.0"
@@ -2488,7 +2473,6 @@ dependencies = [
  "ouroboros",
  "rand 0.7.3",
  "rayon",
- "semver",
  "tempfile",
  "unicode-width",
  "uucore",