kt: add «2490. Circular Sentence»

URL:	https://leetcode.com/problems/circular-sentence/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/circular-sentence.kt

@@ -0,0 +1,14 @@
+class Solution {
+    private data class PartialResult(val last: Character, val circular: Boolean) {
+        fun update(word: String): PartialResult = PartialResult(word[word.length - 1], circular && word[0] == last)
+    }
+
+    fun isCircularSentence(sentence: String): Boolean =
+        sentence.splitToSequence(" ")
+            .scan(PartialResult(sentence[sentence.length - 1], true)) { acc, word ->
+                acc.update(word)
+            }
+            .all {
+                it.circular
+            }
+}