fix(keyborg): Multiple bundles should not override instances

[mathis-m]

Fixes #99
Not sure about #75 as it is stale for so long, that is why I have taken it up myself:

To provide backwards compatibility: prefix changed from:

• c => c_
• k => k_

Id is now synced via the global window object.

Hence:
New Ids with underscore in the id will not collide as the number is synced over the window and JS is single thread.
Old code wont override the new ids because of the underscore.

Outlook:
In general this topic needs to be revisited to ensure that the refs and core instances are grouped by version.
eg:

{
  __keyborg?: {
    vnext: {
      [version: string]: {
        refs: Record<string, Keyborg>;
        core: KeyborgCore;
        lastId: number;
      }
    }
  }
}

[mathis-m]

@miroslavstastny @mshoho @Hotell please have a look at this. It's open for 4months now. We at Avanade are depending on this, this has impact on MSTF products such as D365 when using PCF components. Having a PR stale for so long is really not appreciated.

Thanks