update RulesCommand to print identifiers but not examples

[jpsim]

The previous functionality lost its usefulness IMHO because the rule examples that are also used for unit tests lost their "printability" and readability over time.

This PR greatly simplifies the rules command to just print a list of rule names and identifiers, making this a much easier way to find all the available rules:

$ swiftlint rules
Line Length Rule (line_length)
Leading Whitespace Rule (leading_whitespace)
Trailing Whitespace Rule (trailing_whitespace)
Returning Whitespace Rule (return_arrow_whitespace)
Trailing Newline Rule (trailing_newline)
Operator Function Whitespace Rule (operator_whitespace)
Force Cast Rule (force_cast)
File Line Length Rule (file_length)
Todo Rule (todo)
Colon Rule (colon)
Type Name Rule (type_name)
Variable Name Rule (variable_name)
Type body Length Rule (type_body_length)
Function Body Length Rule (function_body_length)
Nesting Rule (nesting)
Control Statement Rule (control_statement)