feat(iOS): Obj-C convenience accessors on CAPPluginCall

[ikeith]

This branch revisits the Obj-C versions of the CAPPluginCall convenience accessors, deprecates the redundant methods on CAPPlugin, adds test coverage, and fixes a bug with dates.

• Adds a getNumber method for NSNumber values.
• Switches the redundant CAPPlugin accessors to use the call's implementation.
• Marks the redundant CAPPlugin accessors as deprecated.
• Fixes the incorrect handling of NSDate objects in getDate.
• Adds unit tests to verify behavior.

[jcesarmobile]

Shouldn't the bridged types have a getBool like the swift plugin call has?
Having to use NSNumber every time you want a boolean might make users use the deprecated getBool from CAPPlugin class instead as it's easier to get despite it's deprecated.

[ikeith]

@jcesarmobile
Swift cares about types more which is why it has more accessors. But we can add a getBool, although I'm not sure how helpful it is since you can use boolValue and NSNumber:
[call getBool:@"foo" defaultValue:TRUE];
vs
[[call getNumber:@"foo" defaultValue:@TRUE] boolValue];

[jcesarmobile]

If they are using a getBool and they are told that that getBool is deprecated and should use the ones from pluginCall, but there is no getBool there it's not trivial to know that they can use getNumber and cast to bool

[ikeith]

That's a fair point. It probably makes sense to ease the migration from the deprecated methods.