Cordova iOS Cocoapods Integration for Cocoapods Plugins settings

# Feature Request

The "cocoapods" elements in the plugin.xml for the ios platform now allows you to modify the generation of the Podfile to include additional pods and sources.

However there is an element of the Podfile specification that is not supported by the current configuration: plugins
https://guides.cocoapods.org/syntax/podfile.html#plugin

This is necessary if your Pod is hosted by Artifactory as you need to use the cocoapods-art plugin to make the pod available to the build.

https://github.com/jfrog/cocoapods-art

This feature would be another config element "<plugin>" within the "<podspec>" element. It would need to support a "name" attribute and an "options" attribute similar to the "options" attribute of the "<pod>" element. Since every plugin could have their own custom options, there is no use in supporting specific options. Just a generic options attribute should be fine.

So for example
```xml

```

Would generate:
```
plugin 'myPluginName', :sources => [ 'my_source' ]
plugin 'myOtherPlugin'
```

Trace how the existing cocoapods settings in plugin.xml are parsed and turned into the generated iOS Podfile. Add support for a plugin name and generic options, then verify that the generated Podfile contains the requested plugin declarations and options.

Written by the indexing model from the issue text.