Add migration test, refactor connection creation, some minor changes

[tdakkota]

No description provided.

[codecov]

Codecov Report

Merging #176 (3c14ce1) into main (2d04c12) will increase coverage by 1.92%.
The diff coverage is 73.78%.

@@            Coverage Diff             @@
##             main     #176      +/-   ##
==========================================
+ Coverage   69.07%   70.99%   +1.92%     
==========================================
  Files         222      226       +4     
  Lines        6476     6609     +133     
==========================================
+ Hits         4473     4692     +219     
+ Misses       1587     1487     -100     
- Partials      416      430      +14     

Impacted Files	Coverage Δ
telegram/internal/manager/connmode_string.go	0.00% <0.00%> (ø)
telegram/internal/manager/handler.go	0.00% <0.00%> (ø)
telegram/message/audio.go	88.00% <0.00%> (-3.67%)	⬇️
telegram/message/dice.go	100.00% <ø> (ø)
telegram/message/stickers.go	0.00% <0.00%> (ø)
telegram/message/upload.go	0.00% <0.00%> (ø)
telegram/migrate_to_dc.go	45.45% <ø> (ø)
telegram/pool.go	0.00% <0.00%> (ø)
telegram/message/media.go	69.62% <38.46%> (ø)
telegram/cfg.go	40.00% <40.00%> (ø)
... and 32 more

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