feat(gitlab): Add contribution templates for issue

Signed-off-by: Benoit Mortier <benoit.mortier@opensides.be>

.gitlab/issue_templates/Contribution.md

+### Requirements
+
+* Filling out the template is required. Any Enhancement request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
+* All new code requires tests to ensure against regressions
+
+## Descriptive title for this contribution
+
+<!-- required -->
+
+### Step by step description of this contribution
+
+<!-- Required -->
+1. [First Step]
+2. [Second Step]
+3. [and so on...]
+
+### Schemas needed by this contribution
+
+<!-- Describe if schema changes are needed by this contribution -->
+<!-- Describe if new schemas are need for this contribution -->
+
+### Benefits
+
+<!-- Required -->
+<!-- What benefits will be realized with this contribution ? -->
+
+### Possible Drawbacks
+
+<!-- optional -->
+<!-- What are the possible side-effects or negative impacts of this contribution ? -->
+
+### Actual use cases
+
+<!-- optional -->
+<!-- Enter any applicable Issues here -->