Add support for mixed versions in a single ATT&CK Navigator instance

[isaisabel]

As a user of the ATT&CK Navigator, I want to be able to specify the ATT&CK content version to use on a given layer.

• The default version of a layer with no specified ATT&CK version will be the current version of ATT&CK
• Each layer can only have one ATT&CK version
• When creating a layer, allow the user to specify the version of ATT&CK they want to use
  • We need to determine what versions of the data are compatable with the Navigator. Old versions are likely to be missing some object types and fields, e.g mitigations.
  • The first few versions likely didn't have the x-mitre-tactic and x-mitre-matrix objects, which means we can't support those versions. We should keep them in the version list (following the precedent of the versions of ATT&CK page) but we can't actually provide access to those versions
  • where non-crucial data is missing, the UI should be marked appropriately, e.g "data does not include any mitigations." This will also improve support for custom datasets.
• When uploading a layer, determine the ATT&CK version from the layer.
  • Refactor layer file version to versions, which would be structured as an object with keys layer, navigator, and attack for the layer format, navigator, and ATT&CK catalog versions respectively.
  • If the ATT&CK version is not current, ask the user if they want to upgrade (See Add "Layer Upgrade" UI #181)
    • Allow the app to remember the user's preference
      
  • If the ATT&CK version is current, load it immediately
• Restrict layer-layer operations to layers of the same version

[isaisabel]

Example UI for the versions:

However , it should probably follow the format of the versions of ATT&CK page with links to the ATT&CK Website, data on MITRE/CTI, changelog, ETC.

The "quick access" links outside of the expansion panel should always be the current version of the data.

[isaisabel]

A query string (e.g ?upgrade=True) should also be added which allows the user to bypass the "do you want to upgrade" prompt. This will allow the ATT&CK team to use the upgrade UI as an "here's what changed in this version" tool, by linking ?layer=v6upgrade.json&upgrade=True, where v6upgrade is an otherwise empty layer. This will essentially bring users right to the upgrade UI, which doubles as a "what changed in this version of ATT&CK" helper when annotations aren't present.

[isaisabel]

Staged on develop for the upcoming release.