LanguageServers: Rename AutoCompleteEngine => CodeComprehensionEngine

This feels like a better name since the "autocomplete engine" can, in
addition to providing autocomplete suggestions, also find declarations
of symbols and report back the symbols that are defined in a document.

Also, Cpp/ParserAutoComplete has been renamed to CppComprehensionEngine
and Shell/AutoComplete has been renamed to ShellComprehensionEngine.

Userland/DevTools/HackStudio/LanguageServers/Cpp/CMakeLists.txt

@@ -1,5 +1,5 @@
 set(SOURCES
-    ParserAutoComplete.cpp
+    CppComprehensionEngine.cpp
     Tests.cpp
     main.cpp
 )