feat: add quickvc, fix usage of ContentVec, remove onnx support

[34j]

Closes #206

• Significant factoring
• Adds QuickVC

[codecov-commenter]

Codecov Report

Merging #197 (17fa86c) into main (7280012) will increase coverage by 2.90%.
The diff coverage is 21.86%.

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@@            Coverage Diff             @@
##             main     #197      +/-   ##
==========================================
+ Coverage   17.03%   19.93%   +2.90%     
==========================================
  Files          32       38       +6     
  Lines        3517     3241     -276     
  Branches      412      410       -2     
==========================================
+ Hits          599      646      +47     
+ Misses       2902     2579     -323     
  Partials       16       16              

Impacted Files	Coverage Δ
src/so_vits_svc_fork/__main__.py	0.00% <0.00%> (ø)
src/so_vits_svc_fork/gui.py	0.00% <0.00%> (ø)
src/so_vits_svc_fork/modules/mel_processing.py	24.59% <0.00%> (ø)
...vits_svc_fork/preprocessing/preprocess_resample.py	67.14% <ø> (ø)
...rk/preprocessing/preprocess_speaker_diarization.py	0.00% <ø> (ø)
...so_vits_svc_fork/preprocessing/preprocess_split.py	40.74% <ø> (ø)
...so_vits_svc_fork/preprocessing/preprocess_utils.py	100.00% <ø> (ø)
src/so_vits_svc_fork/inference/core.py	19.14% <7.40%> (ø)
..._svc_fork/modules/decoders/mb_istft/_generators.py	12.71% <12.71%> (ø)
src/so_vits_svc_fork/modules/synthesizers.py	18.36% <18.36%> (ø)
... and 20 more

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[34j]

At least it's working now.