Created embedded package for Speckle Connector

[JR-Morgan]

Whats changed

Created embedded package for Speckle Connector

• Involved moving Asset\Speckle Connector folder to Packages\systems.speckle.speckle-unity and creating a package.json file

Why

This allows the connector to be installed using the package manager "Install from git url"

Enter the path below to install. Once this PR is merged, this URL will be shorter (remove #package from the end of the url below)

https://github.com/specklesystems/speckle-unity.git?path=/Packages/systems.speckle.speckle-unity#package

EDIT: Pr is now merged, url is:

https://github.com/specklesystems/speckle-unity.git?path=/Packages/systems.speckle.speckle-unity

TODO:

• Update Docs Unity Install Instructions Update - Package speckle-docs#43