Make SSL optional when selecting SASL Auth

[Fred Bricon]

We have a webview now (#193), but SSL is still required when selecting SASL* auth.
@jnsjunior needs it to be optional (#195).

[Angelo]

It means that we should just remove this validation

vscode-kafka/src/wizards/clusters.ts

Line 389 in 889a606

 if (!(parameters[CLUSTER_SSL_FIELD] === true || parameters[CLUSTER_SSL_FIELD] === 'true')) { 

?

[Fred Bricon]

Changing the severity of the problem allows us to still warn the user and allow them to save the cluster

[Fred Bricon]

@jnsjunior can you please check the CI build from https://github.com/jlandersen/vscode-kafka/actions/runs/1027031973?