New run_sanity_checks mechanism, for SpatiLite

Moved VirtualSpatialIndex check into a new mechanism that should allow
us to add further sanity checks in the future.

To test this I've had to commit a binary sample SpatiaLite database to
the repository. I included a build script for creating that database.

Closes #466

tests/test_inspect.py

@@ -1,30 +0,0 @@
-from .fixtures import app_client
-from datasette.cli import cli
-from click.testing import CliRunner
-import json
-
-
-def test_inspect_cli(app_client):
-    runner = CliRunner()
-    result = runner.invoke(cli, ["inspect", "fixtures.db"])
-    data = json.loads(result.output)
-    assert ["fixtures"] == list(data.keys())
-    database = data["fixtures"]
-    assert "fixtures.db" == database["file"]
-    assert isinstance(database["hash"], str)
-    assert 64 == len(database["hash"])
-    for table_name, expected_count in {
-        "Table With Space In Name": 0,
-        "facetable": 15,
-    }.items():
-        assert expected_count == database["tables"][table_name]["count"]
-
-
-def test_inspect_cli_writes_to_file(app_client):
-    runner = CliRunner()
-    result = runner.invoke(
-        cli, ["inspect", "fixtures.db", "--inspect-file", "foo.json"]
-    )
-    assert 0 == result.exit_code, result.output
-    data = json.load(open("foo.json"))
-    assert ["fixtures"] == list(data.keys())