Add option to process code to set top level folder name

[rt17603]

Original report by Rachel Tunnicliffe (Bitbucket: rt17603, GitHub: rt17603).

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In the process script this currently uses the “domain”, “site” and “height” inputs to construct the expected top level folder name e.g. “TAC_EUROPE_100magl”. We should include an option to supercede this with a different top level folder name supplied in full.