Content Model code improvement 2: Decouple DomToModelContext and editor

[JiuqingSong]

I'll have a bunch of PR to improve Content Model code, and do some clean up.

The goal of this change is to decouple roosterjs-content-model-dom package from editor related logic, so that it can be used as a standalone library to do content transformation. To achieve this goal, I moved all editor related settings out to let editor pass in, includes:

1. zoomScale
2. root RTL
3. selection

Then reorganize the parameter of createDomToModelContext and domToContentModel, now it can still work if nothing is passed in. In that case, content model will work with the following settings:

• Light mode
• Zoom scale = 1
• Root direction is LTR
• There is no selection in document

All these settings are suitable for the case of

• Just read and rewrite content that is not inside an Editor
• Process pasted content before insert them into editor

Then from roosterjs-content-model-editor package, it can gather all those information and pass it into Content Model.

Also to simplify the types, I removed customized selection types for Content Model, but just reuse SelectionRangeEx instead when do Dom to Model conversation.