fix(attachments): add missing file picker confirm

[st3iny]

Nextcloud 29 (stable4.7) and below are not affected.

[st3iny]

/backport to stable5.0

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 23.54%. Comparing base (08688c1) to head (df34ac0). Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
.../components/Editor/Attachments/AttachmentsList.vue	0.00%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #6383 +/- ## ============================================ - Coverage 29.30% 23.54% -5.77% + Complexity 908 454 -454 ============================================ Files 288 247 -41 Lines 13929 11701 -2228 Branches 2203 2202 -1 ============================================ - Hits 4082 2755 -1327 + Misses 9527 8626 -901 Partials 320 320 ``` | [Flag](https://app.codecov.io/gh/nextcloud/calendar/pull/6383/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nextcloud) | Coverage Δ | | |---|---|---| | [javascript](https://app.codecov.io/gh/nextcloud/calendar/pull/6383/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nextcloud) | `15.07% <0.00%> (-0.01%)` | :arrow_down: | | [php](https://app.codecov.io/gh/nextcloud/calendar/pull/6383/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nextcloud) | `59.53% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nextcloud#carryforward-flags-in-the-pull-request-comment) to find out more.

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