(fix) Revive search functionality in "ui-select-ext" components

[samuelmale]

Requirements

• [X] This PR has a title that briefly describes the work done including the ticket number. If there is a ticket, make sure your PR title includes a conventional commit label. See existing PR titles for inspiration.
• [ ] My work conforms to the OpenMRS 3.0 Styleguide and design documentation.
• [X] My work includes tests or is validated by existing tests.

Summary

This PR primarily fixes the search functionality in the "ui-select-ext". There are two main changes:

1. Returned the inlined loader that manages the search state. This gives some visual aid to the user about the search happing in the background.
2. Introduced a new function; fetchSingleItem(uuid: string) to the DataSource interface. This offers a better way of resolving the "field value" in edit mode.

Out of scope

1. Fixed disabled tests
2. Fixed an issue where the component was losing its state on hide (https://openmrs.atlassian.net/browse/O3-3448)
3. Cleanup

Screenshots

Related Issue

• https://openmrs.atlassian.net/browse/O3-3770
• https://openmrs.atlassian.net/browse/O3-3448

Other

[github-actions[bot]]

Size Change: -360 kB (-23.89%) 🎉

Total Size: 1.15 MB

Filename	Size	Change
dist/501.js	0 B	-108 kB (removed)	🏆
dist/572.js	0 B	-252 kB (removed)	🏆

ℹ️ View Unchanged

| Filename | Size | Change | | :--- | :---: | :---: | | `dist/151.js` | 300 kB | 0 B | | `dist/225.js` | 2.57 kB | 0 B | | `dist/277.js` | 1.84 kB | 0 B | | `dist/300.js` | 642 B | 0 B | | `dist/335.js` | 968 B | 0 B | | `dist/353.js` | 3.02 kB | 0 B | | `dist/41.js` | 3.37 kB | 0 B | | `dist/420.js` | 108 kB | 0 B | | `dist/422.js` | 6.8 kB | 0 B | | `dist/514.js` | 253 kB | 0 B | | `dist/540.js` | 2.63 kB | 0 B | | `dist/55.js` | 758 B | 0 B | | `dist/617.js` | 86.9 kB | 0 B | | `dist/635.js` | 14.3 kB | 0 B | | `dist/70.js` | 483 B | 0 B | | `dist/901.js` | 11.8 kB | 0 B | | `dist/99.js` | 691 B | 0 B | | `dist/993.js` | 3.09 kB | 0 B | | `dist/main.js` | 342 kB | +521 B (+0.15%) | | `dist/openmrs-esm-form-engine-lib.js` | 3.67 kB | +4 B (+0.11%) |

_{compressed-size-action}