Update upstream keys format in manifest

[mateumiralles]

More than one upstreamKey should be able to be declared in the manifest per package, for those that have dependencies from multiple upstreamRepos. Upstream keys in manifest should have the following format:

upstream?: {
    upstreamVersion: string;
    upstreamRepo: string;
    upstreamArg: string;
  }[]

Both formats should be supported (the old and this one), but throwing error in case the two are defined in the same manifest.
Its types and schemas in dappmanager and gaBumpUpstreamHandler should be refactored to these changes.

[dappnodedev]

Actually, the format will be:

upstream?: {
    version: string;
    repo: string;
    arg: string;
  }[]