Major revamp to remove the dependency to email regression reports

Use KernelCI API queries directly to get all the regression data. Email reports are still parsed to search for bisections, which aren't stored in the KernelCI database.

The regressions per branch are now shown grouped by test name and first kernel version failed. All the other functionalities are kept the same and the html output is still the same except for the new grouping.

Right now the tracker will get all the regressions existing in the KernelCI database in the last day for the subscribed branches. This will be parameterized in other MRs.