Task: Integrate tufstorage to Archivista store Process

[kairoaraujo]

This issue enables the usage of TUF with Archivista.

It integrates the tufstorage (#236 ) to the store Process of Archivista when it receives an upload of Attestation or Policy.
The tufstorage is used only when the user has configured Archivista to use TUF/RSTUF (#237)

Requires

• Task: Implement the tufstorage in internal #236
• Task: Include TUF configuration for Archivista #237

Feature parent

• Feature|Experimental: Add support to add Policies to TUF #159