feat: add image type support to proxy endpoint

[wa0x6e]

🧿 Current issues / What's wrong ?

The current /proxy endpoint does not support image file, even though we can upload them through /upload/

💊 Fixes / Solution

Add support for /proxy to return images, in addition to json files

Fix #36

🚧 Changes

• /proxy can now return image
• refactoring of the cache system, to support setting and returning both json and image type.
• add tests

🛠️ Tests

[codecov]

Codecov Report

Attention: 73 lines in your changes are missing coverage. Please review.

Comparison is base (4dcdf7a) 32.02% compared to head (bd1f020) 33.57%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #196      +/-   ##
==========================================
+ Coverage   32.02%   33.57%   +1.55%     
==========================================
  Files          15       15              
  Lines         637      676      +39     
  Branches       42       46       +4     
==========================================
+ Hits          204      227      +23     
- Misses        425      441      +16     
  Partials        8        8              

Files	Coverage Δ
src/rpc.ts	0.00% <0.00%> (ø)
src/aws.ts	83.09% <74.07%> (-4.63%)	⬇️
src/utils.ts	48.97% <69.56%> (+13.26%)	⬆️
src/providers/index.ts	0.00% <0.00%> (ø)
src/proxy.ts	0.00% <0.00%> (ø)
src/upload.ts	0.00% <0.00%> (ø)
src/middlewares/useProxyCache.ts	0.00% <0.00%> (ø)

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