Adjust vertical sizing of paste area (#1766)

Related #1739. Stacked on
#1764.

This PR adjusts slightly reduces the initial height of the paste area
(from ~14 to ~10 lines), and allows the user to resize it vertically.

My thinking is that in many cases people probably only paste in short
snippets (such as passwords), so the paste area wouldn’t feel as empty
in this “base case”. Users can still conveniently manage longer text by
resizing the paste area vertically.

<img width="819" alt="Screenshot 2024-03-29 at 15 34 28"
src="https://github.com/tiny-pilot/tinypilot/assets/83721279/cd481e3f-d38e-4cc1-88d4-7d9cbd666f05">

<a data-ca-tag
href="https://codeapprove.com/pr/tiny-pilot/tinypilot/1766"><img
src="https://codeapprove.com/external/github-tag-allbg.png" alt="Review
on CodeApprove" /></a>

---------

Co-authored-by: Jan Heuermann <[email protected]>

app/templates/custom-elements/paste-dialog.html

@@ -6,8 +6,8 @@
     #paste-area {
       display: block;
       width: 100%;
-      height: 20rem;
-      resize: none;
+      min-height: 15rem;
+      resize: vertical;
       box-sizing: border-box;
       padding: 0.25rem 0.5rem;
       background-color: white;