Shims to support multiple Spark versions

[jerrychenhf]

We will need to support multiple Spark versions on a single code base.

The ideal solution is to use Shims to separate version specific code into a Shim layer specific to that version and load the Shim layer at runtime based on the runtime version.

[zhouyuan]

@jerrychenhf
#273

[jerrychenhf]

@zhouyuan Thanks for linking to the previous issue.
I have implemented a shim layer as a template to all OAP projects.
I will first submit to Native SQL Engine repository today. Other component can follow this same approach and add their own.