Replace Explorer .ui gui file with .py

[fdrgsp]

I recreated the sample_explorer gui widget in python and replaced the old .ui file.

[codecov]

Codecov Report

Merging #168 (4eb2e34) into main (b1b0b60) will increase coverage by 1.29%.
The diff coverage is 96.33%.

@@            Coverage Diff             @@
##             main     #168      +/-   ##
==========================================
+ Coverage   81.58%   82.88%   +1.29%     
==========================================
  Files          25       26       +1     
  Lines        2270     2448     +178     
==========================================
+ Hits         1852     2029     +177     
- Misses        418      419       +1     

Impacted Files	Coverage Δ
..._sample_explorer_widget/_sample_explorer_widget.py	82.53% <80.00%> (ø)
...ts/_sample_explorer_widget/_sample_explorer_gui.py	97.08% <97.08%> (ø)
micromanager_gui/_gui_objects/_mm_widget.py	96.93% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b1b0b60...4eb2e34. Read the comment docs.

[tlambert03]

LGTM