Adds sl-copy-button fontawesome icons (#302)

- Changes `sl-copy-button` icons to use fontawesome equivalents so they
fit in with everything else in ReplayWebpage
- Converts sl-icon to use fa-icon for error icon
- Adds missing whitespace

Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>

src/item-info.ts

@@ -181,7 +181,7 @@ class ItemInfo extends LitElement {
               ${certFingerprintUrl
                 ? html`<span
                     ><a target="_blank" href="${certFingerprintUrl}"
-                      >View Certificate</a
+                      >&nbsp;View Certificate</a
                     ></span
                   >`
                 : nothing}