Add anon script and cleans up directory

[heyhaleema]

This PR:

• Cleans up the repository directory e.g. removes unnecessary files and directories, old scripts, etc.
• Renames csc_xnat/ to src/ for clarity
• Adds an updated version of the project anonymisation script e.g. used in the ptavi project and with new series rejection feature

Note

I kept the SOPs i.e. in docs/, and Bash scripts i.e. in src/bash/, despite some of them being obsolete e.g. those related to the iFIND project, primarily because they may (1) be useful for future work e.g. new scripts to use in cron jobs to automate removal of secondary files, and (2) require an updated, rather than deletion e.g. SOP-Data-Checking, SOP-Data-Import, etc.