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>

aurweb/models/official_provider.py

@@ -0,0 +1,34 @@
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.orm import mapper
+
+from aurweb.schema import OfficialProviders
+
+
+class OfficialProvider:
+    def __init__(self,
+                 Name: str = None,
+                 Repo: str = None,
+                 Provides: str = None):
+        self.Name = Name
+        if not self.Name:
+            raise IntegrityError(
+                statement="Column Name cannot be null.",
+                orig="OfficialProviders.Name",
+                params=("NULL"))
+
+        self.Repo = Repo
+        if not self.Repo:
+            raise IntegrityError(
+                statement="Column Repo cannot be null.",
+                orig="OfficialProviders.Repo",
+                params=("NULL"))
+
+        self.Provides = Provides
+        if not self.Provides:
+            raise IntegrityError(
+                statement="Column Provides cannot be null.",
+                orig="OfficialProviders.Provides",
+                params=("NULL"))
+
+
+mapper(OfficialProvider, OfficialProviders)