* Adds ssl support for prometheus query runner.
- Adds possibilty to upload and use of ssl cert, key and ca file in redash ui
* Extends test cases for prometheus query runner.
- Adds secret attribute to configuration schema.
* Fixes wrong timestamps in different timezones in prometheus' testcases.
- Dynamically calculates timestamps in testcases to be robust in
different timezones.
- Adds now datetime function to make it more testable.
* Fixes timestamp in prometheus' testcases which can be wrong depending on timezone.
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Co-authored-by: Masayuki Takahashi <masayuki038@gmail.com>