bisect-kit: Remove the `common.init()` function

To remove the `common.init()` function, this CL makes following changes
1. Let configure be lazy-loaded
2. Load plugins when importing the `bisect_kit` module

BUG=b:254006099
TEST=./run_formatters.sh && ./run_tests.sh

Change-Id: I357a1ec89301e4260b342f8ccc7022bc4dc803be
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/bisect-kit/+/4273069
Reviewed-by: MD Nayeem Jahan Rafi <njrafi@chromium.org>
Tested-by: Ace Wu <acewu@chromium.org>
Commit-Queue: Ace Wu <acewu@chromium.org>
26 files changed