Probe every access review connector on status check

Bad API keys and expired OAuth tokens showed Connected because
probes ran only for OAuth2 and many providers had no ProbeURL.
Add a registry ProbeConnection dispatcher with static, dynamic,
and custom probes so all 41 providers are checked on demand.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/connector/provider/linear.go

@@ -29,7 +29,7 @@ func linearRegistration() *Registration {
 		DisplayName:  "Linear",
 		AuthURL:      "https://linear.app/oauth/authorize",
 		TokenURL:     "https://api.linear.app/oauth/token",
-		ProbeURL:     "https://api.linear.app/graphql",
+		Probe:        probeLinear,
 		OAuth2Scopes: []string{"read"},
 		NewDriver: func(_ context.Context, c *http.Client, _ *coredata.Connector, _ *log.Logger) (drivers.Driver, error) {
 			return drivers.NewLinearDriver(c), nil