kt: add «392. Is Subsequence»

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

kt/is-subsequence.kt

@@ -0,0 +1,20 @@
+class Solution {
+    fun isSubsequence(
+        s: String,
+        t: String,
+    ): Boolean {
+        var i = 0
+
+        for (j in t.indices) {
+            if (i < s.length && t[j] == s[i]) {
+                i++
+            }
+
+            if (i >= s.length) {
+                break
+            }
+        }
+
+        return i == s.length
+    }
+}