misc: Add GH issue template (#3796)

This PR adds:

- A GH issue/bug template

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,23 @@
+---
+name: Bug Report
+about: Report a bug or unexpected behavior
+title: ""
+labels: bug
+assignees: ''
+
+---
+
+### Description
+A clear and concise description of the issue or bug. 
+
+### Expected vs Actual Behavior
+Include what you expected to happen and what actually happened (e.g., when compared with upstream MLIR).
+
+### Steps to Reproduce and a Minimal Working Example (MWE)
+1. Describe the steps to reproduce the issue (commands, etc.).
+2. If applicable, describe the environment (e.g., operating system, Python version, etc.).
+3. Please make your reproducible example as small as possible.  
+It should be self-contained and easy to run.
+
+### Additional Information
+Any extra information that might help debug the issue.