top dir is for microbenchmarks of host function call of policy 2 in my thesis

• this tests the time of host function calls with different policies.
• select what runtime needs to be tested via cargo features.

e2e dir is for end to end benchmarks for both policy 1 and 2 of my thesis.

• guests contain the tests to run
• policies contains the policies used during benchmarking
• test_runtimes are the runtimes that are being benchmarked