Transfer SmartLengthInputFilter license to Tusky (#1384)

* Transfer SmartLengthInputFilter in-header license

Transfer license for file "SmartLengthInputFilter.java" from me (Diego Rossi) to Tusky and therefore also change it from the original Apache 2.0 to currently GPLv3. This was a mistake that has been sitting around for way too long.

* Rewrite SmartLengthInputFilter from Java to Kotlin

This has been done by hand, without the custom copy-paste tool.

* Fix bad references in Java files using SmartLengthInputFilter features

* Shorten code in Java classes referencing SmartLengthInputFilter instance

* Refactor SmartLengthInputFilter from class to singleton Kotlin object

* Move hasBadRatio to become a toplevel function

* Patch up all the files affected by SmartLengthInputFilter changes

* Length in SmartLengthInputFilter is const 500, simplify code accordingly

* More meaningful name for toplevel function for checking trimming ability

* Add missing license header

app/src/main/java/com/keylesspalace/tusky/util/StatusViewHelper.kt

@@ -310,7 +310,7 @@ class StatusViewHelper(private val itemView: View) {
     }
 
     companion object {
-        val COLLAPSE_INPUT_FILTER = arrayOf<InputFilter>(SmartLengthInputFilter.INSTANCE)
+        val COLLAPSE_INPUT_FILTER = arrayOf<InputFilter>(SmartLengthInputFilter)
         val NO_INPUT_FILTER = arrayOfNulls<InputFilter>(0)
     }
 }