chore: add issue template for technical debt (llamastack#2753)

# What does this PR do?
Adds a template for technical debt. Currently we don't support blank
issues so everything filed has to a bug or a feature.
This would allow maintainers as well as community members to track
things we might want to merge to expose the functionality but should be
addressed later. Such things can also be "good first issues" for new
contributors.

## Example of what we constitute as technical debt
Inelegant code solutions, tests we intend to temporarily disable but
would like to restore, CI hacks around infrastructure or installation,
etc.

Signed-off-by: Nathan Weinberg <[email protected]>

Author: nathan-weinberg

.github/ISSUE_TEMPLATE/tech-debt.yml

@@ -0,0 +1,30 @@
+name: 🔧 Tech Debt
+description: Something that is functional but should be improved or optimizied
+labels: ["tech-debt"]
+body:
+- type: textarea
+  id: tech-debt-explanation
+  attributes:
+    label: 🤔 What is the technical debt you think should be addressed?
+    description: >
+      A clear and concise description of _what_ needs to be addressed - ensure you are describing
+      constitutes [technical debt](https://en.wikipedia.org/wiki/Technical_debt) and is not a bug
+      or feature request.
+  validations:
+    required: true
+
+- type: textarea
+  id: tech-debt-motivation
+  attributes:
+    label: 💡 What is the benefit of addressing this technical debt?
+    description: >
+      A clear and concise description of _why_ this work is needed.
+  validations:
+    required: true
+
+- type: textarea
+  id: other-thoughts
+  attributes:
+    label: Other thoughts
+    description: >
+      Any thoughts about how this may result in complexity in the codebase, or other trade-offs.