[web] use `inline` `Content-Disposition` by default (closes #2535734)
since known time we have been serving static file with a `filename` parameter on
the `Content-Disposition` header. But since d74addac92bb we explicitly serve
file as attachment if a filename is provided. However this is valid to have
`inline` disposition and `filename` parameter. This changeset revert this part
of d74addac92bb, going back to `inlined` by default.
`IDownloadable` code explicitly request `attachment` content to preserve
expected behavior.
addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile