Support mTLS in C8 deployment and start process

[barmac]

What should we do?

• Migrate to camunda-8-js-sdk (draft deps: replace zeebe-node with @camunda8/sdk #4233)
• Support mTLS configuration in C8 self-managed (oAuth)

Why should we do it?

Product hub epic: https://github.com/camunda/product-hub/issues/2451

[barmac]

It is unclear to me right now whether we want to support it via UI (file selector instead of secret input), or via configuration. The first one sounds more reasonable though, as the certificate is a way to authenticate to a certain endpoint.

[nikku]

I see two options as viable:

• You specify a set of client certificates via flags (command line) and these will be used
• We have an improved deploy mechanism in place, where connections can be properly maintained. On that dialog you're able to specify the client certificate to use for a particular connection.

[barmac]

For better clarity, below is how it could work in the UI (unstyled):

This is missing an option to decide whether to use a secret or a certificate.

[nikku]

Yep, there you go. This blows up in our users faces. I propose we take this as an action item to make connections configurable outside of the deploy dialog.

[barmac]

The configurable connections are an ages-old issue: #804

[barmac]

@lmbateman Please have a look at this as a potential topic you could help with.