Adds confirm modal for loading data

bookwyrm/static/css/fonts/icomoon.svg

@@ -46,4 +46,5 @@
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 <glyph unicode="&#xe9da;" glyph-name="heart" d="M755.188 896c-107.63 0-200.258-87.554-243.164-179-42.938 91.444-135.578 179-243.216 179-148.382 0-268.808-120.44-268.808-268.832 0-301.846 304.5-380.994 512.022-679.418 196.154 296.576 511.978 387.206 511.978 679.418 0 148.392-120.43 268.832-268.812 268.832z" />
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+<glyph unicode="&#xea36;" glyph-name="download" d="M512-32l480 480h-288v512h-384v-512h-288z" />
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