Implement Session Actions

[miggs125]

What would you like to be added:
The selenium client provides users with an actions object which allows users to send the driver a list of actions to be performed synchronously or asynchronously. This includes, keyUp, keyDown, mouseMove, click, etc. More info on this can be found here

The following seem the most critical and should be implemented first:

• click
• moveToElement
• contextClick
• doubleClick
• sendKeys (this is not the same as the Element Send Keys endpoint)
• keyUp
• keyDown
• moveByOffset
• dragAndDrop

Why is this needed:
This is a very powerful feature of selenium and plumadriver would be missing a lot of functionality if this fails to be implemented

Additional context

[poftadeh]

W3C spec: /session/{session id}/actions

Expands on the basic functionality to be provided by #29.

[poftadeh]

sendKeysToElement() in Session.ts, and WebElement click() will need to be updated as well to use actions.