feat(gallery): display pieces jointes in a gallery

app/assets/stylesheets/gallery.scss

@@ -0,0 +1,66 @@
+.gallery {
+  display: flex;
+  flex-wrap: wrap;
+
+  .gallery-item {
+    display: block;
+  }
+
+  a {
+    background-image: none;
+  }
+
+  .champ-libelle {
+    margin-top: 0.5rem;
+  }
+
+  img {
+    height: 200px;
+    width: 200px;
+    object-fit: cover;
+  }
+
+  .thumbnail {
+    position: relative;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+
+    img {
+      position: relative;
+      z-index: 1;
+    }
+
+    .fr-icon-eye {
+      position: absolute;
+      z-index: 10;
+      background-color: var(--background-default-grey);
+      color: var(--text-active-blue-france);
+      border: 1px solid var(--border-active-blue-france);
+      padding: 0.25rem 0.75rem;
+
+      &:hover {
+        background-color: var(--hover-tint);
+      }
+
+      &:active {
+        background-color: var(--active-tint);
+      }
+    }
+  }
+}
+
+.lg-has-iframe {
+  width: 80% !important;
+  margin-top: 50px;
+}
+
+.lg-icon {
+  --hover-tint: none;
+  --active-tint: none;
+}
+
+.lg-sub-html {
+  background-image: linear-gradient(180deg, rgba(0, 0, 0, 0), rgba(0, 0, 0, 1)) !important;
+  padding: 30px 40px 0 40px !important;
+}