Introduce TSDB service (#31520)

* Introduce TSDB service

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

Co-authored-by: Erik Sundell <erik.sundell87@gmail.com>
Co-authored-by: Will Browne <will.browne@grafana.com>
Co-authored-by: Torkel Ödegaard <torkel@grafana.org>
Co-authored-by: Will Browne <wbrowne@users.noreply.github.com>
Co-authored-by: Zoltán Bedi <zoltan.bedi@gmail.com>

pkg/plugins/manager/testdata/invalid-v2-signature/plugin/MANIFEST.txt

@@ -0,0 +1,28 @@
+
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA512
+
+{
+  "manifestVersion": "2.0.0",
+  "signatureType": "grafana",
+  "signedByOrg": "grafana",
+  "signedByOrgName": "Grafana Labs",
+  "plugin": "test",
+  "version": "1.0.0",
+  "time": 1605809299800,
+  "keyId": "7e4d0c6a708866e7",
+  "files": {
+    "plugin.json": "2bb467c0bfd6c454551419efe475b8bf8573734e73c7bab52b14842adb62886f",
+    "veryImportantFile": "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+  }
+}
+-----BEGIN PGP SIGNATURE-----
+Version: OpenPGP.js v4.10.1
+Comment: https://openpgpjs.org
+
+wqIEARMKAAYFAl+2tJMACgkQfk0ManCIZueB0AIJAT/PWs226MaIu3eDZy4o
+3UH/tIExyY4zR+VSBfTS+Gji5BcIRkIn7bhM1U40KDraDCvQOl3WetgqQkPd
+wcSTJJocAgkBrsrxNz/Nl+vw/usre3Funj0hPVS/6NnJXwe6sVH+gAQfeddz
+MzYTY/gcUVWp8Y7l/Hg44nry0PS3sr5LQ30w/FY=
+=ev+T
+-----END PGP SIGNATURE-----

pkg/plugins/manager/testdata/invalid-v2-signature/plugin/plugin.json

@@ -0,0 +1,16 @@
+{
+  "type": "datasource",
+  "name": "Test",
+  "id": "test",
+  "backend": true,
+  "executable": "test",
+  "state": "alpha",
+  "info": {
+    "version": "1.0.0",
+    "description": "Test",
+    "author": {
+      "name": "Will Browne",
+      "url": "https://willbrowne.com"
+    }
+  }
+}