Add basic sanitization

[CodyCBakerPhD]

This will be a follow-up PR from #70

From discussion

nwb2bids should attempt to 'sanitize' fields in an attempt to 'harmonize' from NWB to BIDS as much as possible; these messages should inform the user that this occurred and offer a flag --no-sanitize to suppress this process

Examples of sanitization:

• labels: BIDS requires dashes separated by underscore between entities whereas the NWB fields these are taken from can be any string (only alphanumeric with +, case-insensitive up to collisions; for example, subject A1 and a1)
• subject species: could utilize https://github.com/dandi/dandi-cli/blob/4401650a9a433a2f37d1857b7e1162249a1c09b7/dandi/metadata/util.py#L336 to harmonize; if no value in map, issue InspectionMessage
• subject sex: sanitize to single character capitalization if any of the allowed BIDS values, complain

Philosophy is, if sanitization is requested, always try to force things through as much as possible, but if we hit a limit, complain.

By default, no sanitization.

Originally posted by @CodyCBakerPhD in #70 (comment)

[CodyCBakerPhD]

Sanitization Proposal

Level 0

No modification of content (BIDS or NWB) at all.

Pull all information out from NWB and write to the target location in BIDS.

Level 1

Fix the session IDs and subject IDs according to the following rules:

• Any non-alphanumeric -> +

Also, write a new column to the requisite tables; nwb_session_ids and nwb_subject_ids, to record provenance and allow mapping to alleviate confusion.

No modification will be made in-place to the NWB contents.

Required for the majority of Dandisets.

If no possible changes are detected, act as if level 0 (even if level 1 is specified).

Level 2

Same as level 1 as far as content, BUT edit all NWB file fields in-place accordingly so that they entirely match (are consistent with) the BIDS counterparts

Level 3+

What other fields are worthy of sanitization?

[CodyCBakerPhD]

Added in #244