[mlir][Target][LLVM] Adds an utility class for serializing operations to binary strings.

**For an explanation of these patches see D154153.**

Commit message:
This patch adds the utility base class `ModuleToObject`. This class provides an
interface for compiling module operations into binary strings, by default this
class serialize modules to LLVM bitcode.

Reviewed By: mehdi_amini

Differential Revision: https://reviews.llvm.org/D154100