PR: Add Remote edditing support

[hlouzada]

Description of Changes

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Included a screenshot or animation (if affecting the UI, see Licecap)

• Created a Helper class RemoteFileHelper using AsyncDispatcher to interact with async api SpyderRemoteFileServicesAPI:
• keeps tracks of the connected APIs per server;
• centralize files operations (read, write);
• provide metadata;
• store remote files metadata with RemoteFileHandle that is stored in FileInfo;
• EditorMainWidget and EditorStack makes use of RemoteFileHelper to create RemoteFileHandle for IO operations and status updates;
• Allow ExplorerWidget and RemoteExplorer to open remote files.

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct: @hlouzada