Add global Vulnerability list #95

[tdruez]

In the context of #95

This PR introduces a new "Vulnerability" list view, available from the "Tools" menu when enable_vulnerablecodedb_access is enabled.

The overall goal is to rank and prioritize package vulnerabilities.

The current implementation focuses on ranking/sorting: Vulnerabilities can be sorted and filtered by severity score. It's also possible to sort by the count of affected packages to help prioritize.
The current progress is about displaying the data collected from VulnerableCode.

@pombredanne @DennisClark I now need your input on how we want to implement the "prioritize" layer, ie: data entered by DejaCode users, specific to a Dataspace.
New fields? Status, priority? What are the actions a user can do about one or a selection of Vulnerabilities? And the consequences of those actions on the Vulnerability behavior in the UI. Let's make sure those new fields are aligned with the output format we plan to support (CycloneDX VEX etc..)

[DennisClark]

@tdruez @pombredanne Prioritization of Vulnerabilities in DejaCode depends on the implementation of these things:

VCIO: Calculate vulnerability risk
aboutcode-org/vulnerablecode#1543

DejaCode: Vulnerabilities policy
#97

I think that those items are the most practical way to support a prioritization process in DejaCode.
We probably need to accelerate development of the calculation of vulnerability risk in VCIO.

[DennisClark]

@tdruez @pombredanne the new Vulnerabilities option from the Tools dropdown menu works quite well, and the performance is surprisingly fast. I think it is probably ready to deploy.