restructure: move el compiler content into lang/

lang/tests/text/examples/transform-suite.el

@@ -0,0 +1,13 @@
+// transform-suite.el — repeat, reverse, strip prefix/suffix/chars.
+fn run_test() -> String {
+    let a: String = str_repeat("ab", 3)                      // "ababab"
+    let b: String = str_reverse("hello")                     // "olleh"
+    let c: String = str_strip_prefix("foobar", "foo")        // "bar"
+    let d: String = str_strip_suffix("hello.md", ".md")      // "hello"
+    let e: String = str_strip_chars(" \thello \n", " \t\n")  // "hello"
+    return a + "|" + b + "|" + c + "|" + d + "|" + e
+}
+
+fn main() -> Void {
+    println(run_test())
+}