Meta: Update jakt build support for fully bootstrapped compiler

Remove the Corrosion dependency, and use the now-builtin
add_jakt_executable function from the Jakt install rules to build our
example application.

By using find_package(Jakt), we now have to set ENABLE_JAKT manually on
both serenity and Lagom at the same time, so the preferred method to do
this for now is:

    cmake -B Build/superbuild<arch><toolchain> \
          -S Meta/CMake/Superbuild \
          -DENABLE_JAKT=ON \
          -DJAKT_SOURCE_DIR=/path/to/jakt

Where omitting JAKT_SOURCE_DIR will still pull from the main branch of
SerenityOS/jakt. This can be done after runing Meta/serenity.sh run.

CMakeLists.txt

@@ -53,8 +53,11 @@ if (NOT HACKSTUDIO_BUILD)
 
     # Host tools, required to generate files for the build
     find_package(Lagom CONFIG REQUIRED)
-    if (TARGET Lagom::jakt)
-        set(ENABLE_JAKT ON)
+
+    if (ENABLE_JAKT)
+        find_package(Jakt CONFIG REQUIRED
+            HINTS "${Lagom_DIR}/.."
+        )
     endif()
 
 endif()