Feat: add issue templates (#1861)

Adds issue templates for bug reports and enhancement.

You can preview what these options look like on my branch
[here](https://github.com/matthew-hagemann/app-center/issues/new/choose)

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -0,0 +1,80 @@
+name: Bug report for the App Center
+description: Report an issue to help the development
+labels:
+  - bug
+assignees:
+  - d-loose
+  - sminez
+  - matthew-hagemann
+body:
+- type: checkboxes
+  attributes:
+    label: Is there an existing issue for this?
+    description: |
+      Please check whether an issue already exists for this feature: https://github.com/canonical/app-center/issues.
+    options:
+    - label: I have searched the existing issues and found none matching what I'm reporting.
+      required: true
+- type: textarea
+  attributes:
+    label: Bug Description
+    description: |
+      Describe the bug clearly and concisely. Include what is the bug and attach screenshots or recordings if needed.
+  validations:
+    required: true
+- type: textarea
+  attributes:
+    label: Steps to reproduce the behavior
+    placeholder: |
+      1. Go to '...'
+      2. Click on '....'
+      3. Scroll down to '....'
+      4. See error
+  validations:
+    required: true
+- type: textarea
+  id: expected_behavior
+  attributes:
+    label: Expected behavior
+    description: |
+      A clear and concise description of what you expected to happen.
+  validations:
+    required: false
+- type: dropdown
+  attributes:
+    label: Ubuntu release
+    description: What version of our Ubuntu are you running?
+    options:
+      - '24.10'
+      - 24.04 LTS
+      - Other (specify in the last field)
+  validations:
+    required: false
+- type: dropdown
+  attributes:
+    label: What architecture are you using?
+    multiple: false
+    options:
+      - amd64
+      - arm64
+      - Other (specify in the last field)
+      - I don't know
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: System info
+    description: |
+      Please run this command in your terminal:
+      ```uname -rv && snap info snap-store snapd```
+      and paste the output here. It will give us information about your system such as the kernel version and the versions of the relevant packages.
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Additional context
+    description: |
+      You can attach screenshots, recordings, logs, or any other information that you think might be helpful. Please remember to anonymize any personal data.
+  validations:
+    required: false
+

.github/ISSUE_TEMPLATE/config.yaml

@@ -0,0 +1,6 @@
+blank_issues_enabled: true
+contact_links:
+  - name: Contact Canonical
+    url: https://ubuntu.com/contact-us/form
+    about: Contact us to get more information
+

.github/ISSUE_TEMPLATE/feature_request.yaml

@@ -0,0 +1,42 @@
+name: Feature request
+description: Suggest an idea for the App Center
+labels:
+  - enhancement
+assignees:
+  - d-loose
+  - sminez
+  - matthew-hagemann
+body:
+- type: checkboxes
+  attributes:
+    label: Is there an existing issue for this?
+    description: |
+      Please check whether an issue already exists for this feature: https://github.com/canonical/app-center/issues?q=label%3Aenhancement.
+    options:
+    - label: I have searched the existing issues and found none matching what I'm reporting.
+      required: true
+- type: textarea
+  attributes:
+    label: Is the feature related to a problem or existing issue?
+    description: |
+      If so, please describe the problem or reference/link the issue number. If not, leave this empty.
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Describe the feature, why the feature matters to you, and what benefits the feature will bring about.
+  validations:
+    required: true
+- type: textarea
+  attributes:
+    label: Describe any alternatives you've considered.
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Additional context
+    description: |
+      Provide any additional context that may be relevant to the feature request.
+  validations:
+    required: false
+