MIRTH-3327: Added framework for custom connector properties plugins. The ConnectorProperties class now contains a set of ConnectorPluginProperties objects, which represent additional properties that extensions can add to certain connectors. On the client side a new plugin point ConnectorPropertiesPlugin was added, which is used to show an additional properties section in the connector panel. Each plugin can choose which connectors it supports with the isSupported method. ConnectorPanel now includes all currently installed connector properties plugin panels, and selectively sets the visibility based on the current transport name (same as it does with the other properties panels). Invalid connector plugin properties are handled in a similar way to how invalid channels are handled. The main difference is that channels with invalid connector plugin properties can still be edited and deployed, and the plugin properties are removed on next save. The user is warned when attempting to edit/import a channel/connector if it contains such properties.

MIRTH-3328: Added new plugin point for connector service extensions. These have the ability to intercept connector service invocations and inject their own logic if need be. On the client side, connector properties plugins also have the ability to intercept the response returned from connector services and perform whatever UI actions they need to. The HTTP and Web Service connectors have been modified to use the new client framework for this, and implement the handleConnectorServiceResponse method.

MIRTH-3329: Connectors and connector properties plugins now have the ability to provide custom coloring, icons, tool-tips, etc. for displaying the connector type in the destination table. In addition, custom decorations from connector properties plugins can be used by the regular connector settings panel to perform the same decoration locally. The destination table now contains ConnectorTypeData objects instead of just the transport name, and the data contains the ConnectorTypeDecoration object which holds all the information needed. The HTTP and Web Service sender connectors have been modified to display a yellow "not configured" color when an HTTPS URL is detected.