Update ImportOrderingRule once Kotlin plugin has support for imports_layout in editorconfig

[romtsn]

As a follow up for #749, there is a number of actions we need to perform after Kotlin plugin is released with support for imports layout via .editorconfig.

• Possibly rename the ij_kotlin_imports_layout property so it matches the one from Kotlin plugin (unlikely though)
• Deprecate idea and ascii predefined styles and print a warning in case of their appearances
• Update editorconfig documentation and show how idea and ascii can be achieved by setting a custom import layout pattern
• Update how "alias" pattern is represented in the editorconfig, so Kotlin plugin understands it

[romtsn]

https://youtrack.jetbrains.com/issue/KT-40353