Update method tracer to use Module#prepend

[tannalynn]

Currently our method tracer uses an eval'ed string with method chaining, however we want to update this to no longer use string eval, and to use Module#prepend instead of method chaining. The args should use (...) on ruby 2.7+.
Also this breaking change may break some our auto instrumented libraries, so updating those uses of add_method_tracer is important as well.
For more details please see #502