Consistent linter rule names

[scripthunter7]

Currently, we have the following linter rules:

if-closed
single-selector
duplicated-modifiers
unknown-preprocessor-directives
duplicated-hint-platforms
duplicated-hints
unknown-hints-and-platforms
invalid-domain-list
invalid-modifiers
inconsistent-hint-platforms
no-short-rules
no-excluded-rules
no-invalid-css-syntax
no-invalid-css-declaration

I propose making the no- prefix consistent across the rule names:

if-directive-balance
one-css-selector-per-rule
no-duplicated-modifiers
no-unknown-preprocessor-directives
no-duplicated-hint-platforms
no-duplicated-hints
no-unknown-hints-and-platforms
no-invalid-domain-list
no-invalid-modifiers
no-inconsistent-hint-platforms
no-short-rules
no-excluded-rules
no-invalid-css-syntax
no-invalid-css-declaration

In addition, it would be worthwhile to rename the if-closed rule since support for else has been added in the meantime. I also propose renaming the single-selector rule to better emphasize that it specifically refers to CSS selectors.