Issue triage: remove old templates, add new ones

Remove the old style Markdown templates and replace with new style yaml
templates. New templates match those used in element-web.

Note that issue labels will been to be renamed to match element-web
before this PR can be merged.

Signed-off-by: Ekaterina Gerasimova <[email protected]>

.github/ISSUE_TEMPLATE/bug.yml

@@ -0,0 +1,74 @@
+name: Bug report for the Element iOS app
+description: Report any issues that you have found with the Element app. Please [check open issues](https://github.com/vector-im/element-ios/issues) first, in case it has already been reported.
+labels: [T-Defect]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for taking the time to fill out this bug report!
+
+        Please report security issues by email to [email protected]
+  - type: textarea
+    id: reproduction-steps
+    attributes:
+      label: Steps to reproduce
+      description: Please attach screenshots, videos or logs if you can.
+      placeholder: Tell us what you see!
+      value: |
+        1. Where are you starting? What can you see?
+        2. What do you click?
+        3. More steps…
+    validations:
+      required: true
+  - type: textarea
+    id: result
+    attributes:
+      label: What happened?
+      placeholder: Tell us what went wrong
+      value: |
+        ### What did you expect?
+
+        ### What happened?
+    validations:
+      required: true
+  - type: input
+    id: device
+    attributes:
+      label: Your phone model
+      placeholder: e.g. iPhoneX
+    validations:
+      required: false
+  - type: input
+    id: os
+    attributes:
+      label: Operating system version
+      placeholder: e.g. iOS14.7.1, under "software version"
+    validations:
+      required: false
+  - type: input
+    id: version
+    attributes:
+      label: Application version
+      description: You can find the version information in Settings -> Help & About. 
+      placeholder: e.g. Element version 1.5.2
+    validations:
+      required: false
+  - type: input
+    id: homeserver
+    attributes:
+      label: Homeserver
+      description: Which server is your account registered on?
+      placeholder: e.g. matrix.org
+    validations:
+      required: false
+  - type: dropdown
+    id: rageshake
+    attributes:
+      label: Have you submitted a rageshake?
+      description:  |
+        Did you know that you can shake your phone to submit logs for this issue? Trigger the defect, then shake your phone and you will see a popup asking if you would like to open the bug report screen. Click YES, and describe the issue, mentioning that you have also filed a bug. Submit the report to send anonymous logs to the developers.
+      options:
+        - 'Yes'
+        - 'No'
+    validations:
+      required: true

.github/ISSUE_TEMPLATE/enhancement.yml

@@ -0,0 +1,36 @@
+name: Enhancement request
+description: Do you have a suggestion or feature request?
+labels: [T-Enhancement]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thank you for taking the time to propose a new feature or make a suggestion.
+  - type: textarea
+    id: usecase
+    attributes:
+      label: Your use case
+      description: What would you like to be able to do? Please feel welcome to include screenshots or mock ups.
+      placeholder: Tell us what you would like to do!
+      value: |
+        #### What would you like to do?
+
+        #### Why would you like to do it?
+
+        #### How would you like to achieve it?
+    validations:
+      required: true
+  - type: textarea
+    id: alternative
+    attributes:
+      label: Have you considered any alternatives?
+      placeholder: A clear and concise description of any alternative solutions or features you've considered.
+    validations:
+      required: false
+  - type: textarea
+    id: additional-context
+    attributes:
+      label: Additional context
+      placeholder: Is there anything else you'd like to add?
+    validations:
+      required: false

changelog.d/pr-4744.misc

@@ -0,0 +1 @@
+Issue templates: modernise and sync with element-web