feat: implement on/off event methods in cip30.experimental

[mirceahasegan]

Context

Some DApps are using experimental CIP30 APIs that allow registering to networkChange/accountChange events.

 /**
 * Deregister the callback from the event.
 *
 * @param {EventName} eventName The event to deregister from. Accepted values are 'accountChange' | 'networkChange'
 * @param {AccountChangeCb | NetworkChangeCb} callback  Must be the same cb reference used on registration.
 */
off: (eventName: Cip30EventName, callback: AccountChangeCb | NetworkChangeCb) =>

/**
 * Register to events coming from the wallet. Registrations are stored by callback reference.
 *
 * @param {EventName} eventName The event to register to. Accepted values are 'accountChange' | 'networkChange'
 * @param {AccountChangeCb | NetworkChangeCb} callback The callback to be called when the event is triggered.
 */
on: (eventName: Cip30EventName, callback: AccountChangeCb | NetworkChangeCb)

Proposed Solution

Add support for these new methods.

Important Changes Introduced

[mirceahasegan]

I found some issues with the implementation. I am working on it...

[mirceahasegan]

Closed due to missing support to push data from content script to injected script, and it makes this feature much more complicated.