chore: set up commitlint, husky, and prettier (#1451)

* chore: add prettier configuration

Signed-off-by: Xe Iaso <me@xeiaso.net>

* format: run prettier tree-wide

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore(prettier): ignore intentionally ungrammatical files

Signed-off-by: Xe Iaso <me@xeiaso.net>

* ci: add PR title lint rule

Signed-off-by: Xe Iaso <me@xeiaso.net>

* ci: add DCO check

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: add commitlint and husky

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: add CONTRIBUTING guidelines

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: set SKIP_INTEGRATION in precommit tests

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: update spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* ci(dco): remove reopened trigger

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: remove dead file

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore(prettier): don't format nginx includes

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/config/testdata/good/git_client.yaml

@@ -1,8 +1,8 @@
 bots:
-- name: allow-git-clients
-  action: ALLOW
-  expression:
-    all:
-    - userAgent.startsWith("git/") || userAgent.contains("libgit")
-    - >
-      "Git-Protocol" in headers && headers["Git-Protocol"] == "version=2"
+  - name: allow-git-clients
+    action: ALLOW
+    expression:
+      all:
+        - userAgent.startsWith("git/") || userAgent.contains("libgit")
+        - >
+          "Git-Protocol" in headers && headers["Git-Protocol"] == "version=2"