settings: Revert "loader" indicator from fontawesome to SVG.
settings: Revert "loader" indicator from fontawesome to SVG.

This reverts loader indicator from the new fontawesome
`icon-button-loading` to previous SVG one, this change is only reflected
to those loaders which use `loader.handlebars` template for
loading indication(because there are some indicators like "Save changes"
in org settings which don't use loader.handlebars).

This main problem with this indicator is that it is bit
inconsistent with other places where we use `loader.handlebars` like
loading Zulip icon which appears while fetching old messages.

showell/zulip,tommyip/zulip,hackerkid/zulip,dhcrzf/zulip,andersk/zulip,rht/zulip,showell/zulip,dhcrzf/zulip,shubhamdhama/zulip,brainwane/zulip,zulip/zulip,synicalsyntax/zulip,showell/zulip,rishig/zulip,kou/zulip,punchagan/zulip,punchagan/zulip,timabbott/zulip,jackrzhang/zulip,synicalsyntax/zulip,kou/zulip,hackerkid/zulip,rishig/zulip,brainwane/zulip,andersk/zulip,jackrzhang/zulip,showell/zulip,tommyip/zulip,synicalsyntax/zulip,punchagan/zulip,kou/zulip,hackerkid/zulip,jackrzhang/zulip,rishig/zulip,rht/zulip,shubhamdhama/zulip,synicalsyntax/zulip,kou/zulip,timabbott/zulip,brainwane/zulip,jackrzhang/zulip,punchagan/zulip,synicalsyntax/zulip,rishig/zulip,andersk/zulip,eeshangarg/zulip,hackerkid/zulip,timabbott/zulip,timabbott/zulip,rht/zulip,eeshangarg/zulip,eeshangarg/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,jackrzhang/zulip,kou/zulip,shubhamdhama/zulip,shubhamdhama/zulip,jackrzhang/zulip,dhcrzf/zulip,zulip/zulip,zulip/zulip,rishig/zulip,hackerkid/zulip,tommyip/zulip,zulip/zulip,jackrzhang/zulip,shubhamdhama/zulip,punchagan/zulip,andersk/zulip,tommyip/zulip,shubhamdhama/zulip,tommyip/zulip,brainwane/zulip,showell/zulip,timabbott/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,zulip/zulip,eeshangarg/zulip,dhcrzf/zulip,tommyip/zulip,eeshangarg/zulip,rishig/zulip,dhcrzf/zulip,punchagan/zulip,rht/zulip,rht/zulip,brainwane/zulip,showell/zulip,timabbott/zulip,tommyip/zulip,dhcrzf/zulip,eeshangarg/zulip,showell/zulip,andersk/zulip,rht/zulip,dhcrzf/zulip,eeshangarg/zulip,kou/zulip,brainwane/zulip,kou/zulip,timabbott/zulip,synicalsyntax/zulip,zulip/zulip,hackerkid/zulip,brainwane/zulip,rishig/zulip,synicalsyntax/zulip,shubhamdhama/zulip