Enforce Go style rules across codebase

Apply five style rules: convert iota string enums to typed
string constants, replace errors.As with errors.AsType,
merge three-group imports into two groups, fix multiline
parameter/argument formatting, and replace fmt.Sprintf URL
construction with net/url.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/accessreview/drivers/google_workspace.go

@@ -22,10 +22,9 @@ import (
 	"net/http"
 	"time"
 
+	"go.probo.inc/probo/pkg/coredata"
 	admin "google.golang.org/api/admin/directory/v1"
 	"google.golang.org/api/option"
-
-	"go.probo.inc/probo/pkg/coredata"
 )
 
 // GoogleWorkspaceDriver fetches user accounts from Google Workspace