Fix compose form submission reloading web interface (#19762)

* Fix compose form submission reloading web interface

Fix regression introduced by #19742

* Fix various compose form buttons being handled like submit buttons

* Fix coding style issue

* Fix missing onClick prop check

app/javascript/mastodon/components/__tests__/__snapshots__/button-test.js.snap

@@ -4,6 +4,7 @@ exports[`<Button /> adds class "button-secondary" if props.secondary given 1`] =
 <button
   className="button button-secondary"
   onClick={[Function]}
+  type="button"
 />
 `;
 
@@ -11,6 +12,7 @@ exports[`<Button /> renders a button element 1`] = `
 <button
   className="button"
   onClick={[Function]}
+  type="button"
 />
 `;
 
@@ -19,6 +21,7 @@ exports[`<Button /> renders a disabled attribute if props.disabled given 1`] = `
   className="button"
   disabled={true}
   onClick={[Function]}
+  type="button"
 />
 `;
 
@@ -26,6 +29,7 @@ exports[`<Button /> renders class="button--block" if props.block given 1`] = `
 <button
   className="button button--block"
   onClick={[Function]}
+  type="button"
 />
 `;
 
@@ -33,6 +37,7 @@ exports[`<Button /> renders the children 1`] = `
 <button
   className="button"
   onClick={[Function]}
+  type="button"
 >
   <p>
     children
@@ -44,6 +49,7 @@ exports[`<Button /> renders the given text 1`] = `
 <button
   className="button"
   onClick={[Function]}
+  type="button"
 >
   foo
 </button>
@@ -53,6 +59,7 @@ exports[`<Button /> renders the props.text instead of children 1`] = `
 <button
   className="button"
   onClick={[Function]}
+  type="button"
 >
   foo
 </button>