Provide configuration to allow camo-media proxying

[zeripath]

Provide configuration to switch on camouflaging of images by capturing and replacing all <img src="..."> attributes with camouflaged urls.

Fix #916

Signed-off-by: Andrew Thornton art27@cantab.net

[codecov-commenter]

Codecov Report

Merging #12802 into master will decrease coverage by 0.01%.
The diff coverage is 11.11%.

@@            Coverage Diff             @@
##           master   #12802      +/-   ##
==========================================
- Coverage   43.23%   43.21%   -0.02%     
==========================================
  Files         650      651       +1     
  Lines       72048    72119      +71     
==========================================
+ Hits        31150    31168      +18     
- Misses      35852    35904      +52     
- Partials     5046     5047       +1     

Impacted Files	Coverage Δ
modules/markup/camo.go	0.00% <0.00%> (ø)
modules/markup/html.go	77.60% <0.00%> (-0.75%)	⬇️
modules/setting/setting.go	47.84% <100.00%> (+0.22%)	⬆️
modules/indexer/stats/queue.go	64.70% <0.00%> (-11.77%)	⬇️
modules/auth/ldap/ldap.go	46.81% <0.00%> (-8.79%)	⬇️
modules/indexer/stats/db.go	43.47% <0.00%> (-8.70%)	⬇️
modules/charset/charset.go	68.53% <0.00%> (-4.50%)	⬇️
modules/queue/workerpool.go	58.77% <0.00%> (-1.23%)	⬇️
modules/log/event.go	56.60% <0.00%> (-0.95%)	⬇️
routers/repo/view.go	37.47% <0.00%> (-0.65%)	⬇️
... and 17 more

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[zeripath]

This will need testing to ensure that I've created this correctly and that it is doing the correct thing.

One of the things that would be good is if we could camo media urls for images stored on gitea itself however there is an issue with permissions which makes the whole thing a bit more complex.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs during the next 2 months. Thank you for your contributions.

[6543]

a smal unit test would be nice ...

... I'll have a look at this

[wxiaoguang]

Is it a general mechanism and does it benefit most users? (maybe it's fine to protect privacy)

After reading the context, I found the camo https://github.com/atmos/camo was dead since 2017 ...... do we really need to support outdated systems? Hmm, https://github.com/cactus/go-camo is a successor.

I would like to keep Gitea itself clear and simple (indeed, not too complex) ..... if the method is general, it's fine to me.

[6543]

👋