parseHTTPSettings can panic with incorrectly provisioned datasources

[njvrzm]

What happened:
A datasource was provisioned with string values instead of booleans in the jsonData. Incorrect types may be correctly interpreted by the Grafana UI - if it's expecting a bool, "false" and "true" are interpreted as bools; if it's expecting a string, it won't display anything for an int - but the sdk panics in parseHTTPSettings because there are unprotected type assertions that are violated.

What you expected to happen:
If jsonData settings are the wrong type, a meaningful error should be returned. (This should probably also happen in the UI, but it needs to happen here in any case.)

How to reproduce it (as minimally and precisely as possible):

1. Provision a datasource with yaml - I tested with ElasticSearch.
2. Include in the jsonData an incorrectly-typed setting, like tlsSkipVerify: "true" or basicAuthUser: 42
3. Load the datasource and run "save and test"
4. See the panic in the returned response

Environment:

• SDK version: since v0.96.0
• Grafana version: Probably any