[FR] Implement some stock Suggestion Providers

[michaelrog]

Inspiration from Laravel Ignition:
https://github.com/facade/ignition/tree/master/src/SolutionProviders

[michaelrog]

ServiceUnavailableHttpException

• Add suggestion: Visit the control panel to finish an update.
• Invokable: Link to CP.
• Maybe also work in a prepareErrorMessage() hook, since the exception has a blank message by default.

[michaelrog]

Common database-related setup errors (c.f. craftcms/cms#6718 (comment))

• No DB connection: Craft can’t connect to the database. Check your connection settings.
• Error querying the info table row: Craft can’t fetch the `[info table]` table row. Exception: [exception message]
• Unknown issue querying the info table row: Craft can’t fetch the `[info table]` table row.