[MLIR][LLVM] Expose type translator from LLVM to MLIR Type

This commit moves the type translator from LLVM to MLIR to a public header for use by external projects or other code.

Unlike a previous attempt (https://reviews.llvm.org/D104726), this patch moves the type conversion into separate files which remedies the linker error which was only caught by CI.

Differential Revision: https://reviews.llvm.org/D104834