Integrate peh into datajoint read in

[jess-breda]

• [x] Write function to deal with dropping other lengths in (pd-peh)
• [ ] add drop_sessions to main code body
• [x] write a function to deal with dropping 1 extra
• [ ] clean up find & fix function and break into smaller
• [ ] create pd_dict with correct lengths, convert to df & deal with crashes/len 9
• [ ] write a function to get peh data for a whole session or sessions into a df
• [ ] merge dfs
• [ ] iterate over animals