UI: Add capabilities service

[hellobontempo]

Description

Since we're moving away from checking capabilities in the ember data model, this adds a new capabilities service so permissions checks can happen more readily anywhere in the codebase.

✅ enterprise test

sample implementation

export default class MyClass extends Component {
  @service capabilities;
  
  backend = 'my-engine';
  permissions 

  // template helper
  canRead = (path) => this.capabilities.canRead(`${this.backend}/data/${path}`)
}

{{#if (await (this.canRead "my-secret"))}}
  <SecretComponent  />
{{/if}}

TODO only if you're a HashiCorp employee

• Backport Labels: If this PR is in the ENT repo and needs to be backported, backport
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  • If this fixes a critical security vulnerability or severity 1 bug, it will also need to be backported to the current LTS versions of Vault. To ensure this, use all available enterprise labels.
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  of a public function, even if that change is in a CE file, double check that
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  break any tests. Sometimes ENT only tests rely on public functions in CE
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[github-actions]

CI Results:
All Go tests succeeded! ✅

[github-actions]

Build Results:
All builds succeeded! ✅

[hellobontempo]

could also call this @permissions if we're worried about confusing it with the @lazyCapabilities method

[hellobontempo]

move this to addon so in templates we can do things like

{{#if (await (this.capabilities.canRead "secret/data/my-secret"))}}
   Show something...
{{/if}}

[hashishaw]

Good idea! Would love some sort of README about this, if nothing else than to establish that this is the newest pattern and we're moving away from capabilities on models.

A couple other improvements we could make here are caching (so we don't re-fetch the API for paths we already have) and passing multiple paths in the same capabilities call. This would be an especially useful improvement in places like KV, where there are multiple paths to check for the backend.

[hashishaw]

preliminary comments!

[hashishaw]

Very nice! 🚀