fix(snackbar): add type="button"

[igdmdimitrov]

Closes #17638

Description

Add type="button" to snackbar component

Type of Change (check all that apply):

• Bug fix
• New functionality
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes)
• Documentation
• Demos
• CI/CD
• Tests
• Changelog
• Skills/Agents

Component(s) / Area(s) Affected:

Snackbar

How Has This Been Tested?

• Unit tests
• Manual testing
• Automated e2e tests

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them
• Accessibility (ARIA, keyboard navigation, focus management) has been verified

[Copilot]

Copilot review overview

🟢 Approval recommended

The focused implementation correctly resolves the reported behavior and includes appropriate regression coverage.

Review effort: Balanced
Findings: None

What changed in this PR

Prevents the snackbar action button from implicitly submitting a containing form.

Changes:

• Sets the default action button’s type to button.
• Adds unit coverage for the button type.
• Documents the fix in the changelog.

File	Description
snackbar.component.html	Adds the explicit button type.
snackbar.component.spec.ts	Verifies the rendered type attribute.
CHANGELOG.md	Records the form-submission fix.

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[mddragnev]

This should be 22.3.0

[mddragnev]

@igdmdimitrov
The issue still reproduces. Add a toolbar with the pinning or hiding action, open it, type something in the search input and press Enter. The page refreshes.

With type="button" on the snackbar, the form no longer has a submit button. But the HTML spec still allows implicit submission when a form with no submit button has only one text-like input: pressing Enter in that input submits the form. The column actions search input is that one input, so Enter submits the form.

Adding type="button" to individual buttons won't cover this. We need a more general fix that cancels the default action of Enter for inputs inside the grid.