Make clientSecretAlias configurable

[paullatzelsperger]

Feature Request

When ParticipantContexts are created via IH's Identity API, it automatically creates an STS account (if STS is embedded in IH).
In doing so, a client_secret is generated (using a pluggable StsClientSecretGenerator). However, there currently is no way
to influence the alias, under which the client_secret is stored in the Vault, instead, it is hard-coded to "<participant-id>-sts-client-secret".

This is obscure, and could theoretically cause collisions in the Vault.

Which Areas Would Be Affected?

ParticipantContext API

Why Is the Feature Desired?

Configurability, avoid collisions in the Vault

Solution Proposal

Add to the ParticipantManifest a map of extensible properties