feat: Added support of AMP to all PyTorch training scripts

[fg-mindee]

This PR introduces the following modifications:

• added option to run the training in AMP
• updated information logged into W&B
• fixed sample plotting in trainings
• fixed compatibility of DBNet with data type different from fp32

Any feedback is welcome!

[codecov]

Codecov Report

Merging #604 (a4de6c4) into main (2335b6f) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #604   +/-   ##
=======================================
  Coverage   96.06%   96.06%           
=======================================
  Files         110      110           
  Lines        4265     4265           
=======================================
  Hits         4097     4097           
  Misses        168      168           

Flag	Coverage Δ
unittests	96.06% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
doctr/models/detection/core.py	97.61% <100.00%> (ø)
doctr/utils/geometry.py	98.78% <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 2335b6f...a4de6c4. Read the comment docs.

[charlesmindee]

Thanks!