Fix lots of spelling errors (#7751)

* Fix a typo

* Fix lots of spelling errors

* Fix a few more spelling mistakes

* s/parsable/parseable/

* Don't touch the third party files

* Cloneable is the preferred C# term

* Copyable is the preferred C++ term

* Revert "s/parsable/parseable/"

This reverts commit 534ecf7675222f39d98928c7e1489b56b004b774.

* Revert unparseable->unparsable corrections
diff --git a/objectivec/DevTools/compile_testing_protos.sh b/objectivec/DevTools/compile_testing_protos.sh
index 021e03d..69c32f9 100755
--- a/objectivec/DevTools/compile_testing_protos.sh
+++ b/objectivec/DevTools/compile_testing_protos.sh
@@ -95,7 +95,7 @@
 # -----------------------------------------------------------------------------
 RUN_PROTOC=no
 
-# Check to if all the output files exist (incase a new one got added).
+# Check to if all the output files exist (in case a new one got added).
 
 for PROTO_FILE in "${CORE_PROTO_FILES[@]}" "${OBJC_TEST_PROTO_FILES[@]}"; do
   DIR=${PROTO_FILE%/*}