add ffi_util package for FFI related util & add @ffi_util.RawFunction type for capture-free function

Author: Guest0x0

ffi_util/ffi_util.mbti

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+package moonbitlang/core/ffi_util
+
+// Values
+
+// Types and methods
+pub type RawFunction
+
+// Type aliases
+
+// Traits
+

ffi_util/moon.pkg.json

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+{}

ffi_util/raw_function.mbt

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+/// A compiler builtin type for raw functions, i.e. functions without any capture.
+/// This is useful when passing callbacks to FFI.
+/// Here `T` must be a function type in `RawFunction[T]`
+pub type RawFunction[T]