[jaeger] more flexible TLS variables

[puffitos]

What this PR does

Adds the possibility to mount a secret with TLS certificates & keys that contains more than one value. The standard secret mounted always expects the ca-cert.pem key to be present, which makes activating TLS complicated in non-default scenarios.

Which issue this PR fixes

• Fixes #513
• Possibly related to #443

Checklist

• [x] DCO signed
• [x] Commits are GPG signed
• [x] Chart Version bumped
• [x] Title of the PR starts with chart name ([jaeger] or [jaeger-operator])
• [x] README.md has been updated to match version/contain new values

[puffitos]

Many thanks for the quick reaction 👏