feat: Add HasLabelAsText interface to NativeButtonElement

[joelpop]

Description

Elements having their labels in their text (such as buttons) must implement a new, method-less interface HasLabelAsText in their element tester (such as NativeButtonElement for the NativeButton component and ButtonElement for the Button component) in order for the withCaption[Containing] selectors to work for them.

Related Flow change for vaadin/testbench#1183

Type of change

• Bugfix
• Feature

Checklist

• I have read the contribution guide: https://vaadin.com/docs/latest/guide/contributing/overview/
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.

Additional for Feature type of change

• Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

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[github-actions]

Test Results

1 101 files  ± 0  1 101 suites  ±0   1h 22m 3s ⏱️ +25s
7 004 tests ± 0  6 955 ✅ ± 0  49 💤 ±0  0 ❌ ±0 
7 347 runs   - 30  7 288 ✅  - 28  59 💤  - 2  0 ❌ ±0 

Results for commit e8f1f64. ± Comparison against base commit f046a79.

♻️ This comment has been updated with latest results.

[mcollovati]

Needs formatting. Other than that LGTM

[sonarcloud]

Quality Gate passed

Issues
37 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.5.0.alpha1 and is also targeting the upcoming stable 24.5.0 version.