Auth: Allow expiration of API keys (#17678)

* Modify backend to allow expiration of API Keys

* Add middleware test for expired api keys

* Modify frontend to enable expiration of API Keys

* Fix frontend tests

* Fix migration and add index for `expires` field

* Add api key tests for database access

* Substitude time.Now() by a mock for test usage

* Front-end modifications

* Change input label to `Time to live`
* Change input behavior to comply with the other similar
* Add tooltip

* Modify AddApiKey api call response

Expiration should be *time.Time instead of string

* Present expiration date in the selected timezone

* Use kbn for transforming intervals to seconds

* Use `assert` library for tests

* Frontend fixes

Add checks for empty/undefined/null values

* Change expires column from datetime to integer

* Restrict api key duration input

It should be interval not number

* AddApiKey must complain if SecondsToLive is negative

* Declare ErrInvalidApiKeyExpiration

* Move configuration to auth section

* Update docs

* Eliminate alias for models in modified files

* Omit expiration from api response if empty

* Eliminate Goconvey from test file

* Fix test

Do not sleep, use mocked timeNow() instead

* Remove index for expires from api_key table

The index should be anyway on both org_id and expires fields.
However this commit eliminates completely the index for now
since not many rows are expected to be in this table.

* Use getTimeZone function

* Minor change in api key listing

The frontend should display a message instead of empty string
if the key does not expire.

pkg/services/sqlstore/migrations/apikey_mig.go

@@ -78,4 +78,8 @@ func addApiKeyMigrations(mg *Migrator) {
 		{Name: "key", Type: DB_Varchar, Length: 190, Nullable: false},
 		{Name: "role", Type: DB_NVarchar, Length: 255, Nullable: false},
 	}))
+
+	mg.AddMigration("Add expires to api_key table", NewAddColumnMigration(apiKeyV2, &Column{
+		Name: "expires", Type: DB_BigInt, Nullable: true,
+	}))
 }