Improve setup checks API

[come-nc]

Summary

The idea here is to avoid using the name as a key in the array as the name of setup checks is translated.
Before:

{
    "dav": {
        "Checking for DAV system address book": {
            "severity": "success",
            "description": "No outstanding DAV system address book sync.",
            "linkToDoc": null
        }
    },
    "security": {
        "Checking for old user imported certificate": {
            "severity": "success",
            "description": null,
            "linkToDoc": null
        },
        "Code integrity": {
            "severity": "info",
            "description": "Integrity checker has been disabled. Integrity cannot be verified.",
            "linkToDoc": null
        },

After:

{
    "dav": {
        "OCA\\DAV\\SetupChecks\\NeedsSystemAddressBookSync": {
            "name": "Checking for DAV system address book",
            "severity": "success",
            "description": "No outstanding DAV system address book sync.",
            "linkToDoc": null
        }
    },
    "security": {
        "OCA\\Settings\\SetupChecks\\CheckUserCertificates": {
            "name": "Checking for old user imported certificate",
            "severity": "success",
            "description": null,
            "linkToDoc": null
        },
        "OCA\\Settings\\SetupChecks\\CodeIntegrity": {
            "name": "Code integrity",
            "severity": "info",
            "description": "Integrity checker has been disabled. Integrity cannot be verified.",
            "linkToDoc": null
        },

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)