add jwt support, support timeseries, fix error handling and fix dependencies

[visualcortex-team]

What this PR does / why we need it:

The current implementation of this plugin has a few issues relating to Alerts:

• The Google JWT File Authentication Type is not implemented.
• The alert response does not support the Format as Timeseries (only Table works).
• Project ID is not correctly used by the plugin.
• Grafana parameters (like ${__from:date:seconds}) are not correctly substituted.
• Dependencies were largely out of date.

Which issue(s) this PR fixes:

This PR aims to fix the above issues.

Fixes #

Special notes for your reviewer:

Release note:

Fixes `Alert` functionality:
- The `Google JWT File` Authentication Type is now supported.
- The alert response supports the `Format as` `Timeseries`.
- Project ID/Default Project ID is now correctly used by the plugin.
- Grafana parameters (like `${__from:date:seconds}`) are substituted.

[ofir5300]

Great contribution @visualcortex-team !

Fixes #301
Fixes #303
Fixes #305