Add UTF-8 validation documentation and tests for proto2, proto3, and editions for Java Protobuf

PiperOrigin-RevId: 923673073

Author: protobuf-github-bot

google3/third_party/java_src/protobuf/current/javatests/com/google/protobuf/utf8validation/lite.awk

@@ -0,0 +1,25 @@
+# Remove code enclosed by "BEGIN FULL-RUNTIME" and "END FULL-RUNTIME" to
+# create the lite-only version of a test file.
+
+BEGIN {
+  in_full_runtime = 0;
+}
+
+/BEGIN FULL-RUNTIME/ {
+  in_full_runtime = 1;
+  next;
+}
+
+/END FULL-RUNTIME/ {
+  in_full_runtime = 0;
+  next;
+}
+
+in_full_runtime {
+  # Skip full runtime code path.
+  next;
+}
+
+{
+  print;
+}