[jit] Use the proper method to resolve classes

For the opcodes sizeof, mkrefany and refanyval the jit was resolving the operand tokens directly from the image.

In dynamic scenarios where the tokens are stored in the wrapper data, this triggered TypeLoadExceptions.

This patch uses mini_get_class, as used everywhere else, to resolve the operand tokens of those opcodes, and adds tests for those opcodes in the DynamicMethod tests.

This patch is licensed under the MIT/X11 license.