[Outreachy Task Submission] Fix Missing Search Button Value Text

[Chiemezuo]

Introduction

The search form component in both the Data and Map view has a problem. The search button has only an icon and has no value text. While this is just a stylistic choice, it raises an issue with any accessibility checking tool. It does this because a button having no value text is a violation of WCAG Success Criterion 1.1.1 (Level A) - Non-text content. See. See a screenshot of the pertinent component:

Note the search icon

How to Test the PR

Manually Testing

1. Open your browser and log into your running Ushahidi deployment (from localhost).
2. Navigate to either the data or map section.
3. Try right-clicking on the search form at the top of the screen and selecting 'inspect'.
4. View the properties, and look for a span element with a class of mzima-button__text. See screenshot below:
   
5. You will not see any text in it.
6. Stop the running Ushahidi deployment in your terminal.
7. Checkout to this PR branch.
8. Re-run your Ushahidi deployment.
9. Repeat steps 1-4.
10. You will see a value in the span element this time around, and this text will be visually hidden.

Using an Accessibility Checker

If you use a tool like WAVE evaluation tool, it's as simple as following steps 1 and 2 above, and then turning on the browser extension. It will flag the issue. Checkout to the PR and do this again, you will notice the issue is no longer flagged.

Dependency

It has a dependency on a previous PR

Fixes

It partially fixes #4805

[Angamanga]

Thank you for your contribution 🙏

[Angamanga]

@Chiemezuo I already approved this but please go ahead and remove the !important here as well 🙏

[Chiemezuo]

Alright! @Angamanga
Consider that done.
Thank you! 🥳