Possibility to specify VO role while creating the proxy

[Soap2G]

Currently there seems to be no way to request a specific role while creating the proxy for the FTS renewal cronjob.

It would be useful to have the possibility of requesting a role, as in some storage configurations is easier to map a VO attribute to an internal account, rather than mapping directly the DN of the X509.

[maxnoe]

The default entry point uses {% if RUCIO_FTS_VOMS is defined -%}-voms {{ RUCIO_FTS_VOMS }}{%- endif %} -timeout 5, so it should be possible to ask for a voms role, using this syntax:

RUCIO_FTS_VOMS: '<vo name>:/<vo name>/Role=<voms role name>'