Improve --centre_name and --upload_tpa arguments usage

[ochkalova]

Description of feature

Currently --centre_name is mandatory regardless of what mode is executed. According to ENA, it is not required for non brokers:

The center_name attribute defines the submitting institution. The center name is automatically assigned from submission account details except for broker accounts. Brokers should provide a center name which reflects the institute where the data was generated. For brokers, the broker_name field is automatically assigned at time of submission.

Also, only GENOMESUBMIT actually uses --centre_name. ASSEMBLYSUBMIT don't use it even though it's required in the input.

TODO:

• Investigate where center name is used
• Make it optional
• Rename to --center_name

Same with --upload_tpa input. It only used in assemblysubmit