Add export option

[murilo-cunha]

Add option for show or diff to export the terminal contents as a HTML, text or SVG string

[codecov]

Codecov Report

Merging #60 (39badd2) into main (eeb84c7) will decrease coverage by 0.42%.
The diff coverage is 86.20%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #60      +/-   ##
==========================================
- Coverage   96.21%   95.78%   -0.43%     
==========================================
  Files          28       28              
  Lines        1481     1520      +39     
==========================================
+ Hits         1425     1456      +31     
- Misses         56       64       +8     

Impacted Files	Coverage Δ
databooks/git_utils.py	92.20% <ø> (-0.10%)	⬇️
databooks/cli.py	89.43% <71.42%> (-1.33%)	⬇️
databooks/tui.py	88.46% <83.78%> (-11.54%)	⬇️
tests/test_cli.py	100.00% <100.00%> (ø)
tests/test_tui.py	100.00% <100.00%> (ø)