Rename BOOTSEL to PICOBOOT, disable mass storage in bootsel mode

lib/client/client.go

@@ -78,12 +78,12 @@ func (c *Client) roundTrip(req any) (any, error) {
 	return c.receive(id)
 }
 
-func (c *Client) BOOTSEL() error {
-	resp, err := c.roundTrip(&RequestBOOTSEL{})
+func (c *Client) PICOBOOT() error {
+	resp, err := c.roundTrip(&RequestPICOBOOT{})
 	if err != nil {
 		return err
 	}
-	if _, ok := resp.(*ResponseBOOTSEL); !ok {
+	if _, ok := resp.(*ResponsePICOBOOT); !ok {
 		return fmt.Errorf("unexpected response: %T", resp)
 	}
 	return nil