Adding micr_XPCTzarr dataset

[chourroutm]

Addition of an example dataset for the XPCT suffix for microscopy in the OME-Zarr (NGFF) file format.

[effigies]

Rebased to simplify merging. Apologies, I didn't realize this was your main branch.

Two small suggestions you can merge directly through github.

[effigies]

@bids-standard/maintainers This PR uses a BIDS-URI. These are supported by the schema validator but not the legacy validator. Do we just want to exclude this dataset from legacy validation, or fall back to the subject-relative path?

[sappelhoff]

Do we just want to exclude this dataset from legacy validation

+1 to exclude from legacy validation

[effigies]

Did https://github.com/bids-standard/bids-validator/pull/2069 instead. Running locally, only EMPTY_FILES complains:

❯ bids-validator/bin/bids-validator ../examples/micr_XPCTzarr
bids-validator@1.14.9-dev.0
	1: [ERR] Empty files not allowed. (code: 99 - EMPTY_FILE)
		./sub-01/ses-01/micr/sub-01_ses-01_sample-brain_XPCT.ome.zarr/0/0/0/0

	Please visit https://neurostars.org/search?q=EMPTY_FILE for existing conversations about this issue.

	1: [WARN] Tabular file contains custom columns not described in a data dictionary (code: 82 - CUSTOM_COLUMN_WITHOUT_DESCRIPTION)
		./samples.tsv
			Evidence: Columns: sample_info  not defined, please define in: /samples.json

	Please visit https://neurostars.org/search?q=CUSTOM_COLUMN_WITHOUT_DESCRIPTION for existing conversations about this issue.

        Summary:                  Available Tasks:        Available Modalities: 
        12 Files, 136.75KB                                Microscopy            
        1 - Subject                                                             
        1 - Session                                                             


	If you have any questions, please post on https://neurostars.org/tags/bids.