ci: Add issue and PR assigner

Adds actions that will automatically assign users to reviews
and issues

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

.github/workflows/issue.yml

@@ -0,0 +1,18 @@
+name: Issue assignment
+
+on:
+    issues:
+        types: [opened]
+
+jobs:
+    auto-assign:
+        runs-on: ubuntu-latest
+        permissions:
+            issues: write
+        steps:
+            - name: 'Auto-assign issue'
+              uses: pozil/auto-assign-issue@v2
+              with:
+                  repo-token: ${{ secrets.USER_TOKEN }}
+                  assignees: d3zd3z, nordicjm, de-nordic, davidvincze
+                  allowSelfAssign: true

.github/workflows/pr.yml

@@ -0,0 +1,17 @@
+name: PR assignment
+
+on:
+    pull_request:
+        types: [opened, edited, synchronize, reopened]
+
+jobs:
+    auto-assign:
+        runs-on: ubuntu-latest
+        permissions:
+            issues: write
+        steps:
+          - uses: actions/checkout@v1
+          - uses: ohnogumi/auto-reviewers@v0.0.5
+            with:
+                token: "${{ secrets.USER_TOKEN }}"
+                config: "CODEOWNERS"