[IDEA] Add cli execution

[halvardssm]

Hi! I would be interested in using this module for cli execution in a CI pipeline without having to write my own script. Would you be open to adding a cli extension of this module, or accept a PR for it?

Example:

deno run https://deno.land/x/semver/cli.ts valid "1.2.3" // "1.2.3"
deno run https://deno.land/x/semver/cli.ts valid "a.b.c" // null
deno run https://deno.land/x/semver/cli.ts clean "  =v1.2.3   " // "1.2.3"
deno run https://deno.land/x/semver/cli.ts satisfies "1.2.3" "1.x || >=2.5.0 || 5.0.0 - 7.2.3" // true
deno run https://deno.land/x/semver/cli.ts gt "1.2.3" "9.8.7" // false
deno run https://deno.land/x/semver/cli.ts lt "1.2.3" "9.8.7" // true
deno run https://deno.land/x/semver/cli.ts minVersion ">=1.0.0" // "1.0.0"

[halvardssm]

@justjavac Could you make a release with the cli update?