fix first entry delete and add bulk delete confirmation(cdli-tablet)

Contributes #2623

Fixes: #2561

Description

• fix first entry delete not working due to nested HTML forms
• add confirmation dialog for bulk delete button

Type of PR

• This PR is a fix.

Technicalities

• added 'block' => true to Form->postLink() so hidden delete forms render outside the deleteAll form, fixing the nested form conflict
• added <?= $this->fetch('postLink') ?> after Form->end() to render the deferred forms
• replaced Form->submit() with Form->button() with confirm option for bulk delete confirmation

Videos

Before

After

Checklist:

• My pull request has a descriptive title (not a vague title like "Update index.md").
• My pull request targets the phoenix/develop branch of the repository.
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no visible errors.