[data.tbx11k] Re-structure database to accomodate bbox annotation querying

src/ptbench/data/tbx11k/v2-fold-6.json

src/ptbench/data/tbx11k/v2-fold-7.json

src/ptbench/data/tbx11k/v2-fold-8.json

src/ptbench/data/tbx11k/v2-fold-9.json

src/ptbench/data/tbx11k/v2-others-vs-atb.json

src/ptbench/data/typing.py

src/ptbench/models/typing.py