Remove hierarchy level information from Secrets

[wkl3nk]

Currently, Secrets carry information about their level in the hierarchy: One of OrganizationId, ProductId or RepositoryId.
As ORT Server evolved over time, Secrets are more and more identified by their name, and less and less by their id.
While in the UI when creating a Secret this hierarchy information is included, the dynamic secret resolution process when .ort.env.yml file is in place, is lenient, and having the choice of multiple passwords, it chooses the most specific one (Repository over Product over Organization).

This is bad. On one hand, it is pretended that you can exactly define what Secret from what level is used, on the other hand there is lenient business logic that just uses the secret's name and does not care about the level.

Proposal:

• Let's get rid off the level information in the Secrets - have them all on the level of the Organization
• As a replacement for the levels, let's have a change history for Secrets in the UI, showing who has changed which Secret for which reasons. So still many users can work independently with secrets.

[mnonnenmacher]

Let's get rid off the level information in the Secrets - have them all on the level of the Organization

That would mean that the product and repository admin roles become mostly useless, because they could not configure secrets anymore.