feat: Changed admin panel style theme

[orronai]

• Added a template of admin html files
• Added a css file contains the style of the navbar
• Changed the requirements of flask-admin in order to support bootstrap4

[sourcery-ai]

Sourcery Code Quality Report

Merging this PR leaves code quality unchanged.

Quality metrics	Before	After	Change
Complexity	1.12 ⭐	1.12 ⭐	0.00
Method Length	31.20 ⭐	31.20 ⭐	0.00
Working memory	6.40 🙂	6.40 🙂	0.00
Quality	83.86% ⭐	83.86% ⭐	0.00%

Other metrics	Before	After	Change
Lines	73	73	0

Changed files	Quality Before	Quality After	Quality Change
lms/lmsweb/admin.py	83.86% ⭐	83.86% ⭐	0.00%

Here are some functions in these files that still need a tune-up:

File	Function	Complexity	Length	Working Memory	Quality	Recommendation

Legend and Explanation

The emojis denote the absolute quality of the code:

• ⭐ excellent
• 🙂 good
• 😞 poor
• ⛔ very poor

The 👍 and 👎 indicate whether the quality has improved or gotten worse with this pull request.

---

Please see our documentation here for details on how these metrics are calculated.

We are actively working on this report - lots more documentation and extra metrics to come!

Help us improve this quality report!

[codecov]

Codecov Report

Merging #285 (ac585c7) into master (07cafa7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #285   +/-   ##
=======================================
  Coverage   78.98%   78.98%           
=======================================
  Files          55       55           
  Lines        2346     2346           
=======================================
  Hits         1853     1853           
  Misses        493      493           

Impacted Files	Coverage Δ
lms/lmsweb/admin.py	93.33% <ø> (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 07cafa7...ac585c7. Read the comment docs.