misc enhancements

[sreichl]

• [x] double memory after fail in normalize (and correct) rule -> already the case
• [x] check if all env export rules have 1GB only memory requirement
• [x] add HVF flag, where one can define the number of highly variable features to be continued with with 0 meaning all (if the number is higher than provided features then take also all) --breaking change--
• [x] pseudobulk: add total count as metadata