Speed up read_airr

[grst]

Description of feature

Loading AIRR data with 1.5M rows takes ~10 minutes. This is not too bad, but could be made less annoying

• Make validation optional (I expect the validation of the airr implementation takes a good chunk of that time)
• Parallelization (read different parts of the file in parallel - or first read into pandas, parse several chunks of the dataframe in parallel)
• Progress bar (this at least shows that this will eventually finish)

[grst]

@felixpetschko is this also something you would consider as part of your optimizations?

[felixpetschko]

I'll have a look and see whether this can be done with reasonable effort 👍