Improve command aliasing

[fmbenhassine]

As of v3.4, creating an alias for a command is done as follows:

CommandRegistration commandRegistration() {
	return CommandRegistration.builder()
		.command("mycommand")
		// define alias as myalias
		.withAlias()
			.command("myalias")
			.and()
		// define alias as myalias1 and myalias2
		.withAlias()
			.command("myalias1", "myalias2")
			.and()
		.build();
}

The DSL methods command("alias").and() are repetitive. I suggest to shorten them as follows:

CommandRegistration commandRegistration() {
	return CommandRegistration.builder()
		.command("mycommand")
		// define a single alias
		.withAlias("myalias")
		// or define multiple ones at once
		.withAlias("myalias1", "myalias2")
		.build();
}

[fmbenhassine]

Might be related to #1127

[fmbenhassine]

I didn't see that it was also possible to alias the group:

[..]
.withAlias()
   .command("alias1")
   .group("Alias Group")
   .and()
[..]

So the shortened syntax I suggested previously does not make sense anymore (how to pass the group as part of the new method signature .withAlias("myalias1", "myalias2")?)

I think the best way to improve command aliasing would be to resolve it as part of #1127 (which BTW mentions aliasing: [..] This could be done for withOption, withTarget, withAlias, withErrorHandling, withHelpOption and withExitCode [..]), something like:

// before
CommandRegistration commandRegistration() {
	return CommandRegistration.builder()
		.command("mycommand")
		// define alias
		.withAlias()
			.command("myalias")
                        .group("myalias group")
			.and()
		.build();
}

// after
CommandRegistration commandRegistration() {
	return CommandRegistration.builder()
		.command("mycommand")
		// define alias
		.withAlias(aliasSpec - > aliasSpec.command("myalias").group("myalias group"))
		.build();
}