We move templates related to listing streams in left pannel of
stream settings overlay to stream_settings folder by making
following changes:
* Rename `subscriptions.hbs` to `browse_streams_list.hbs`.
* Move `settings_stream_list.hbs` to stream_settings folder.
* Rename `subscription.hbs` to `browse_streams_list_item.hbs`.
* Move `settings_stream_list_item.hbs` to stream_settings folder.
Following changes are done to subscription_table_body.hbs:
* Rename subscription_table_body.hbs to stream_settings_overlay.hbs,
to have a uniform naming pattern for stream settings templates.
* Move it to stream_settings folder.
This commmit does following two changes to subscription_settings.hbs:
* Rename subscription_settings to stream_settings to have a uniform
naming pattern for stream settings.
* Move it to stream_settings folder.
We used html_submit_button to pass text to be present in the modal
submit button. There are only two possible options as of now -
"Confirm" and "Save changes" and the correct one can be determined
using is_confirm_modal parameter. So, we remove this paramter for
now and we can add it later if we have more type of modals using
this widget.
We use subs as a common variable name for a collection of stream
data structure used in settings, in lot of modules. So this
rename clears a bunch of related shadowed variables.