Meta+Userland: Add jakt as an optional Lagom Tool

We can now use ENABLE_JAKT to pull jakt as a host tool and use it to
pre-process .jakt files into .cpp files for use in serenity applications

Meta/CMake/jakt.cmake

@@ -0,0 +1,39 @@
+#
+# Builds the jakt bootstrap compiler as a host tool for Lagom to compile files written in jakt
+#
+
+include(FetchContent)
+
+FetchContent_Declare(
+  Corrosion
+  GIT_REPOSITORY https://github.com/corrosion-rs/corrosion.git
+  GIT_TAG v0.2.1
+)
+
+FetchContent_MakeAvailable(Corrosion)
+
+FetchContent_Declare(jakt
+    GIT_REPOSITORY https://github.com/SerenityOS/jakt.git
+    GIT_TAG main
+    GIT_SHALLOW TRUE
+)
+
+# Allow developers to skip download/update steps with local checkout
+if (JAKT_SOURCE_DIR)
+    set(FETCHCONTENT_SOURCE_DIR_JAKT ${JAKT_SOURCE_DIR} CACHE PATH "Developer's pre-existing jakt source directory" FORCE)
+    message(STATUS "Using pre-existing JAKT_SOURCE_DIR: ${JAKT_SOURCE_DIR}")
+endif()
+
+FetchContent_GetProperties(jakt)
+if (NOT jakt_POPULATED)
+    FetchContent_Populate(jakt)
+    corrosion_import_crate(MANIFEST_PATH "${jakt_SOURCE_DIR}/Cargo.toml")
+    corrosion_set_hostbuild(jakt)
+    add_executable(Lagom::jakt ALIAS jakt)
+    corrosion_install(TARGETS jakt RUNTIME COMPONENT Lagom_Runtime)
+    # NOTE: See lagom-install-config.cmake for hax required to get Lagom::jakt to show up on install
+    install(DIRECTORY "${jakt_SOURCE_DIR}/runtime"
+            DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/jakt
+            FILES_MATCHING PATTERN "*.h"
+                           PATTERN "*.cpp")
+endif()