RevEng: add tests

[lajones]

Part of #830. Need to come up with a testing strategy and implement more tests for Reverse Engineering.

[lajones]

Added end-to-end test on release branch (dnx451 only) with commit 1d973a1.

[bricelam]

(Copying my comment from an earlier PR:)

I think for functional tests, it would good to hit a database and/or compile code. The two big functional scenarios I see are:

• Create various database objects, verify SqlServerMetadataModelProvider outputs a correct model
• Create various models, generate code, verify code, compile code, verify model

[lajones]

Merged the end-to-end test for dnx451 into dev branch with commit 776124e.

[lajones]

E2E test is updated to work on dnxcore50 as well. See #2452.

[lajones]

Added compilation test with #2575

[rowanmiller]

@lajones what is still outstanding here?

[lajones]

The standard RevEng capabilities are covered through the end-to-end tests, but would like to add more unit tests.

[rowanmiller]

Closing, feel free to incrementally add coverage as you work on things.