Convert Java to Kotlin action: minor improvements

Do not show "Do you want to backup?" dialog if no java files are selected
Improve the code
Change dialog title to Convert Java to Kotlin
Actually cancel if user presses cancel
Formatter: introduce "Put left brace on new line option", support this option for "if/else" expressions
Formatter tests: Fix wrong test file extension (prevented a bunch of formatter tests from running)
Formatter tests: Separate test model for tests with inverted settings
Formatter refactoring: Rewrite spacing rules to kotlin, place all rules in one place
Formatter tests: minor, enhance test for function literal
Formatter: Move custom rule down by eliminating conflicting rule
Formatter tests: minor, enhance "IfSpacing" test
Formatter: left brace formatting for "while" statement
Formatter: left brace formatting for "try/catch/finally"
Formatter: left brace formatting for "do while"
Formatter: left brace formatting for "for in ..."
Formatter: left brace formatting for function declaration
Formatter: left brace formatting in class/trait/class object/object/object literal declarations
Formatter: improve indentation rules for when entries
Formatter: left brace formatting for "when" expression and "when" entries
Formatter: UI for left brace placement option
Formatter: support "else on new line" option
Formatter: support "while on new line" option
Formatter: support "catch on new line" and "finally on new line" options