Admin config: Preset filters

[gtk-grafana]

Some admins want to define specific filters that are always visible in the UI.

Some organizations have specific flows that they want users to go down, for example having the ability to define a specific variable that will always be visible in the UI, instead of needing to tell users of Explore logs that they need to navigate to the breakdown tabs and find a specific label (or set of labels), would be valuable for expanding usage and preventing the need to create so many dashboards.

[gtk-grafana]

Variables might not be the correct solution here, just need something to address the use-case of bringing in users that might not be familiar with Explore Logs UI and guiding them down an admin configured/blessed path