users: change user role

[arurao]

• Identified the issue which this PR solves.
• Read the CONTRIBUTING document.
• Code builds clean without any errors or warnings.
• Added appropriate tests for any new functionality.
• All new and existing tests passed.
• Added comments in the code, where necessary.
• Ran make check to catch common errors. Fixed any that came up.

Description:
This PR provides the ability for admins to change user roles.

Which issue(s) this PR fixes:
Part of #1247

Describe any introduced user-facing changes:
Admins will be able to see 'Edit' icon on the user details page.

After that, there will be an option to check/uncheck the admin role option.

Checking it will set the user as admin, unchecking will set the role to user.
If the logged-in user is already an admin, unchecking the checkbox will show a warning notice mentioning the change in role and it's effects.

Describe any introduced API changes:
A split logic has been applied to the updateUser mutation.
Whenever the role field is specified, the logic will go to a different store method that updates the user role, else it will go to the store update a user logic.
This decision was made since even though there is currently no UI for updateUser fields like name, email, etc that might change in the future (and is possible today via the graphql playground) editing user fields like name, email, etc could be done by the user themselves. But in the case of changing user's role, this operation is strictly limited to admins only. No non-admin user should be allowed to make themselves as an admin. So, in order to keep the two different permission checks separate for updating user fields and changing user role, the logic is split up accordingly.

[mastercactapus]

A few high-level things we could

[Forfold]

Edit: Fixed in latest commit

I got this error when trying to update a user other than myself to admin, in the UI console:

The network tab showed this response on the request:

{
  "errors": [
    {
      "message": "Cannot query field \"setUserRole\" on type \"Mutation\".",
      "locations": [{ "line": 2, "column": 3 }],
      "extensions": { "code": "GRAPHQL_VALIDATION_FAILED" }
    },
    {
      "message": "Unknown type \"SetUserRoleInput\".",
      "locations": [{ "line": 1, "column": 1 }],
      "extensions": { "code": "GRAPHQL_VALIDATION_FAILED" }
    }
  ],
  "data": null
}