Allow creation of entities of any type with base field value parsing

[chrisolof]

Resolves #194.

This was built and tested in a D10 environment. Pairs really well with jhedstrom/DrupalDriver/pull/271.

Opens up stuff like this:

Given "commerce_product_variation" entities:
  | title | type     | field_manufacturer | sku      | field_category | price:number | price:currency_code | status |
  | TNT   | product  | ACME               | TNT-01   | Excavation     | 200          | USD                 | 1      |
  | Anvil | product  | ACME               | ANVIL-01 | Metal          | 450          | USD                 | 1      |
  And "commerce_product" entities:
    | title | type     | variations | stores         | status |
    | TNT   | product  | TNT        | ACME Web Store | 1      |
    | Anvil | product  | Anvil      | ACME Web Store | 1      |

Deletes the entities out after scenario in reverse order so as to respect dependent entity setups.

Otherwise pretty much follows the node/term/user creation and cleanup patterns. But now we can set up entities of any type.