Use dynamic file type associations in IntelliJ-Eta

[carymrobbins]

Relates to: carymrobbins/intellij-haskforce#358

Both HaskForce and IntelliJ-Eta associate .hs files. This means that the two plugins will interfere with each other. We need to associate file types dynamically, possibly by checking for the existence of EtaFrameworkType in the file's IntelliJ module.

See -

• EtaFileTypeFactory.java
• EtaFrameworkType.java