[feat] add an option to use the sample barcode in the FASTQ header

[nh13]

Requirements:

1. Add command line option to specify that index sequences are in the read name header (--sample-barcode-in-fastq-header)
2. Require that (a) no index reads are given to the tool, and (b) that the provided read structure does not have sample barcode bases
3. Demultiplexer::demultiplex supports extracting sample barcode from read name header
4. Update README with new option

Unit tests:

1. Demultiplexer struct can use the sample barcode in the FASTQ header for both single index and dual index runs
2. If given an input FASTQ, fail when a sample barcode segment in the read structure is given and when --sample-barcode-in-fastq-header is being used
3. If given a path prefix with an index FASTQ (e.g. I2),fail when --sample-barcode-in-fastq-header is being used

Manually tested:

1. Failed if given input FASTQs and read structure with sample barcodes while using --sample-barcode-in-fastq-header
2. Failed if given FASTQ prefix (with an index file) while using --sample-barcode-in-fastq-header (NB: read structure inferred from file name)
3. Succeeded if given input FASTQs and no read structure with sample barcodes while using --sample-barcode-in-fastq-header
4. Succeeded if given FASTQ prefix (with no index files) while using --sample-barcode-in-fastq-header (NB: read structure inferred from file name)

[nh13]

Added so I can print these upon an error message, not just in the usage.

[nh13]

Print the link to this repo and the support email upon any error.