improvements to creation of templates, component templates, and dashboards on startup

[mmguero]

Currently during startup we only create certain items if we see the arkime-sessions3* index hasn't been created yet:

• dashboard import
• templates
• etc.

However, if the startup process is interrupted we might get the index template created but not everything else.

We should probably either have some kind of check that we do on something that happens at the end of all of this setup that we use instead, or the other option is to just be a little more explicit in checking and importing things that don't exist regardless.

The other part of this is making sure we get new updates/templates/etc. on an "upgrade" vs. requiring a fresh install.

There is existing code to check the template to see if it's changed (see here) but it's only done for secondary data stores. This should probably be done for primary data stores as well.

[mmguero]

Here are the changes that have been made:

• a "full import check" is performed in the following situations
  • on startup of the dashboards-helper container
  • 86400 seconds (one day) from the time of the last full import check
  • within a few minutes of the removal of the file /tmp/shared-objects-created in the dashboards-helper container

Here's what a "full import check" entails:

• templates
  • a sha256 sum of the combined templates is calculated and the templates are imported (overwriting existing templates) if the previously stored hash (if any) matches the template and component files to imports
• index patterns
  • if templates (see above) were imported, corresponding index patterns are created, overwriting existing patterns
• dashboards
  • Dashboard JSON files have an .updated_at field with an ISO 8601-formatted date (e.g., 2024-04-29T15:49:16.000Z). For each dashboard, we query to see if the object exists and get the .updated_at field for the .type == "dashboard" objects. If the dashboard doesn't already exist, or if the file-to-be-imported date is newer than the old one, then import the dashboard.
• anomaly detectors
  • behavior very similar to the dashboards section above
• opensearch UI tweaks (e.g., dark mode, default dashboard, etc.)
  • these settings are set every time a full import check triggers. this may not be ideal, but it's not a dealbreaker for now
• alerting objects (notification channels and monitors)
  • these will attempt to import every time a full import check triggers, but will fail silently if they already exist. this is also not ideal, but it's not a dealbreaker for now.