investigate striping of BigData files

`lfric_atm` requires a range of static files for initialisation, collectively known as BigData

On Lustre, BigData benefits from striping `lfs (get|set)stripe`

naive striping set all files, whatever the size, to `-c 32 -S 4m -p disk`

a more considered stripin implementation should be investigated, for example:

It is suggested to have the following stripe sizes for file size:
* 1 to 100 MiB - 1 stripe
* 100 MiB to 1GiB - 2 to 4 stripes
* 1 GiB to 100 GiB - 4 to 8 stripes
* It is suggested to use more than 8 stripes for input files if this shows direct benefit in performance tests.