Fix/login providers

[petersg83]

⚠ need to merge #7054 before
fix #7206
fix #6570

Should be be merged at the same time as: strapi/strapi-examples#164

• Provider doc is updated
• use of "redirect_url" is simplified in front

NB:
I tested all providers. They all work except:

• twitter (the twitter user email was not given in the response api, so strapi can't match it with a strapi user)
• instagram (the api is most likely outdated)
• vk (api is outdated, min version is 5.21)

Thoses bugs need to be fixed, but not in this PR.

[codecov]

Codecov Report

Merging #7132 into master will increase coverage by 0.05%.
The diff coverage is 48.64%.

@@            Coverage Diff             @@
##           master    #7132      +/-   ##
==========================================
+ Coverage   26.17%   26.22%   +0.05%     
==========================================
  Files        1130     1131       +1     
  Lines       15415    15433      +18     
  Branches     2439     2443       +4     
==========================================
+ Hits         4035     4048      +13     
- Misses       9561     9565       +4     
- Partials     1819     1820       +1     

Flag	Coverage Δ
#front	18.26% <0.00%> (-0.01%)	⬇️
#unit	53.14% <100.00%> (+0.17%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...s/strapi-admin/admin/src/containers/Admin/index.js	63.82% <ø> (ø)
...admin/admin/src/containers/Roles/EditPage/index.js	2.77% <0.00%> (-0.80%)	⬇️
...admin/admin/src/containers/Roles/ListPage/index.js	0.00% <0.00%> (ø)
...ermissions/admin/src/components/PopUpForm/index.js	0.00% <0.00%> (ø)
packages/strapi-admin/services/metrics.js	100.00% <100.00%> (ø)
packages/strapi-admin/services/role.js	94.11% <100.00%> (+0.14%)	⬆️
packages/strapi-admin/services/user.js	82.56% <100.00%> (+0.66%)	⬆️
packages/strapi/lib/services/metrics/sender.js	100.00% <100.00%> (ø)

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[soupette]

LGTM for the front-end part

[lauriejim]

LGTM

[lauriejim]

Is this PR ready to merge?

[petersg83]

Is this PR ready to merge?

I'm waiting for a review from @alexandrebodin

[lauriejim]

Can you please target the documentation branch.

[alexandrebodin]

@lauriejim this needs to be merged into master as there is code changes :)

[alexandrebodin]

Works like a charm

[derrickmehaffy]

Thank you for this @petersg83 works great

[veerjainATgmail]

Just tested it with the Github provider and replaceLoginApp branch login-React exaple.
Works perfect.! Thanks. The login-React example is simpler now.

Notes:
If someone is facing github error "Authorization callback URL mismatch error", that means url is not mentioned in the config/server.js file. Pasting the snapshot for the working case.

http://localhost:1337/admin/plugins/users-permissions/providers
https://github.com/settings/applications
and, config/server.js - strapi server code.