refactor driver.py and kernel_interface

[ksagiyam]

This PR is to refactor driver.py and kernel_interface.

We introduce new classes TSFCFormData and TSFCIntegralData (that mimic ufl.FormData and ufl.IntegralData), in the constructors of which we preprocess ufl.FormData and ufl.IntegralData as much as possible, extracting only essential information for KernelBuilders. This narrows down the scope of KernelBuilders.
TSFCFormData can also take multiple ufl.FormDatas and combine them.

Several tasks done in driver.compile_integral were factored out and turned into methods of KernelBuilderMixin class in kernel_interface.common: compile_ufl, compile_gem, etc. This simplifies driver.compile_integral a lot, and the contents of this function can now optionally be exposed in the problem solving environments' TSFC interface (such as firedrake/tsfc_interface.py), which allows for application of intermediate operations during compilation that only problem solving environments understand (such as finite element basis transformations).

Firedrake needs to be adapted to these changes:
firedrakeproject/firedrake#1864

[ReubenHill]

@ksagiyam can you rebase onto master?

[ksagiyam]

Rebased. Thanks.