fastannotate: use sysstr to deal with some attributes We are now Python3 only and attribute are always unicode string. So no needs to managed them using bytes.

hgweb: use sysstr to set attribute on diff option Attribute identifier should be `str` not `bytes`.

hgweb: use sysstr to get attribute on diff option Attribute identifier should be `str` not `bytes`.

diff-option: move attributes handling to sysstr Attributes are `str` and should be handled as such.

compression: use sysstr to specify attribute to fetch for priority These are attributes so they should be `str`.

smartset: set attribute using sysstr instead of bytes We do not needs bytes here.

cachedlocalrepo: use sysstr for attribute name of "file of interest" The first item is an attribute name, the second one is a filename. So the first one can (and should) be a `str`.