Ensure dialog is scrolled to top when opened

[knolleary]

Description

Fixes FlowFuse/forge-ui-components#149

Ensures a re-opened dialog is scrolled to the top.

[codecov]

Codecov Report

Merging #2623 (ba5f5bc) into main (e225b74) will decrease coverage by 37.59%.
Report is 3 commits behind head on main.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main   #2623       +/-   ##
==========================================
- Coverage   39.80%   2.22%   -37.59%     
==========================================
  Files         527     527               
  Lines       18368   18368               
  Branches     4314    4314               
==========================================
- Hits         7312     409     -6903     
- Misses      11056   17959     +6903     

Flag	Coverage Δ
backend	?
frontend	2.22% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
...rontend/src/ui-components/components/DialogBox.vue	0.00% <0.00%> (ø)

... and 176 files with indirect coverage changes