add case [in]sensitivity tests + add OfficialProvider model

`ci` in this context means "Case Insensitive".
`cs` in this context means "Case Sensitive".

New models created:
    - OfficialProvider
      This was required to write a test for checking that
      OfficialProviders behaves as we expect, which was the starter
      for the original aurblup bug.

New tests created:
    - test_official_provider

Modified tests:
    - test_package_base: add ci test
    - test_package: add ci test
    - test_session: add cs test
    - test_ssh_pub_key: add cs test

Signed-off-by: Kevin Morris <kevr@0cost.org>

test/test_official_provider.py

@@ -0,0 +1,75 @@
+import pytest
+
+from sqlalchemy.exc import IntegrityError
+
+from aurweb.db import create
+from aurweb.models.official_provider import OfficialProvider
+from aurweb.testing import setup_test_db
+
+
+@pytest.fixture(autouse=True)
+def setup():
+    setup_test_db("OfficialProviders")
+
+
+def test_official_provider_creation():
+    oprovider = create(OfficialProvider,
+                       Name="some-name",
+                       Repo="some-repo",
+                       Provides="some-provides")
+    assert bool(oprovider.ID)
+    assert oprovider.Name == "some-name"
+    assert oprovider.Repo == "some-repo"
+    assert oprovider.Provides == "some-provides"
+
+
+def test_official_provider_cs():
+    """ Test case sensitivity of the database table. """
+    oprovider = create(OfficialProvider,
+                       Name="some-name",
+                       Repo="some-repo",
+                       Provides="some-provides")
+    assert bool(oprovider.ID)
+
+    oprovider_cs = create(OfficialProvider,
+                          Name="SOME-NAME",
+                          Repo="SOME-REPO",
+                          Provides="SOME-PROVIDES")
+    assert bool(oprovider_cs.ID)
+
+    assert oprovider.ID != oprovider_cs.ID
+
+    assert oprovider.Name == "some-name"
+    assert oprovider.Repo == "some-repo"
+    assert oprovider.Provides == "some-provides"
+
+    assert oprovider_cs.Name == "SOME-NAME"
+    assert oprovider_cs.Repo == "SOME-REPO"
+    assert oprovider_cs.Provides == "SOME-PROVIDES"
+
+
+def test_official_provider_null_name_raises_exception():
+    from aurweb.db import session
+    with pytest.raises(IntegrityError):
+        create(OfficialProvider,
+               Repo="some-repo",
+               Provides="some-provides")
+    session.rollback()
+
+
+def test_official_provider_null_repo_raises_exception():
+    from aurweb.db import session
+    with pytest.raises(IntegrityError):
+        create(OfficialProvider,
+               Name="some-name",
+               Provides="some-provides")
+    session.rollback()
+
+
+def test_official_provider_null_provides_raises_exception():
+    from aurweb.db import session
+    with pytest.raises(IntegrityError):
+        create(OfficialProvider,
+               Name="some-name",
+               Repo="some-repo")
+    session.rollback()