Add permission checks on app edit and instance add

[knolleary]

Fixes #3949

Description

Adds appropriate needsPermission checks on the following pieces of UI to hide them from users who don't have permission to do these actions:

• Application Instances - 'add instance' button visibility
• Edit Application details
• Delete Application

A couple other cases were identified in 3949 - in particular around Device Groups. However, Device Groups are an EE only feature - and the way our front-end permission checks currently work means we cannot use the existing needsPermission mixin as-is. I'll raise a separate issue with details, but no need to block making these quick improvements.

Related Issue(s)

Checklist

• [ ] I have read the contribution guidelines
• [ ] Suitable unit/system level tests have been added and they pass
• [ ] Documentation has been updated
  • [ ] Upgrade instructions
  • [ ] Configuration details
  • [ ] Concepts
• [ ] Changes flowforge.yml?
  • [ ] Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • [ ] Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production

Labels

• [ ] Includes a DB migration? -> add the area:migration label

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.72%. Comparing base (94e85f9) to head (d80a5ca).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #4060 +/- ## ======================================= Coverage 78.72% 78.72% ======================================= Files 284 284 Lines 13008 13008 Branches 2897 2897 ======================================= Hits 10240 10240 Misses 2768 2768 ``` | [Flag](https://app.codecov.io/gh/FlowFuse/flowfuse/pull/4060/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FlowFuse) | Coverage Δ | | |---|---|---| | [backend](https://app.codecov.io/gh/FlowFuse/flowfuse/pull/4060/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FlowFuse) | `78.72% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=FlowFuse#carryforward-flags-in-the-pull-request-comment) to find out more.

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[knolleary]

There are quite a few places where direct navigation gets you to a view you can't use. I'm not going to pull on that thread here - we know the user can't do anything once on that view.