Add GitHub PR and Issue templates

Add the GitHub PR and Issue templates used by the KubeVirt org.

Signed-off-by: Felix Matouschek <fmatouschek@redhat.com>

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,31 @@
+<!-- This form is for bug reports and feature requests ONLY!
+Also make sure that you visit our User Guide at https://kubevirt.io/user-guide/
+-->
+
+**Is this a BUG REPORT or FEATURE REQUEST?**:
+
+> Uncomment only one, leave it on its own line:
+>
+> /kind bug
+> /kind enhancement
+
+
+**What happened**:
+
+**What you expected to happen**:
+
+**How to reproduce it (as minimally and precisely as possible)**:
+
+
+**Anything else we need to know?**:
+
+**Environment**:
+- KubeVirt version (use `virtctl version`):
+- Kubernetes version (use `kubectl version`):
+- common-templates version:
+- VM or VMI specifications:
+- Cloud provider or hardware configuration:
+- OS (e.g. from /etc/os-release):
+- Kernel (e.g. `uname -a`):
+- Install tools:
+- Others: