Custom grouping for builds/boots/tests on detailed views

This is concerning the table showing build, boot or test details on detail views like [`/tree///`](https://dashboard.kernelci.org/tree/mainline/master/1590cf0329716306e948a8fc29f1d3ee87d3989f) or [`hardware/`](https://dashboard.kernelci.org/hardware/bcm2711-rpi-4-b?et=1784557800&st=1784125800).

Currently, tests are shown grouped by `test.path`, while builds and boots are not grouped at all.

My proposal is to allow user to select (possibly nested) grouping rules (or completely remove them). Groupings would display aggregated counts and be expandable, as they are now on the tests table. Some grouping rules that might be useful:
- path (boots and tests)
- config (builds)
- status
- tree/branch (on `/hardware`)
- hardware_id (on `/tree`)
- compiler, architecture (builds)
- lab (boots and tests)
- date (what granularity?)

Start with the detailed /tree/// and /hardware/ views, comparing the existing test.path grouping with the ungrouped builds and boots tables. Done means users can choose nested or no grouping, see aggregated counts, and expand groups for the proposed path, config, status, tree/branch, hardware_id, compiler, architecture, lab, and date dimensions.

Written by the indexing model from the issue text.