SQLite: add a value generator for Int32

[borgdylan]

Trying out the SQLite provider leaving key generation to EF fails as the only built-in generator is for Guids (not supported under SQLite).

[bricelam]

The GUID generator will work; they get mapped to BLOB values by Microsoft.Data.SQLite.

#361 adds a value generator for columns that map to INTEGER PRIMARY KEY columns (including AUTOINCREMENT ones). By default, this means long properties.

The remaining work for this issue, I would consider to be a duplicate of #302.

[rowanmiller]

Discussed in triage and decided that we should just make Int32 properties work for identity (since this is a very common pattern in domain classes). We'll handle this by using a long column in the database - similar to what we do to make GUIDs work.

[bricelam]

Per our decision, this may now depend on #242

[bricelam]

Resolved by #2006