feat: rich gRPC errors

[moul]

• adds a new errcode.Has helper
• adds a new errcode.Codes helper
• adds a new errcode.Is helper
• switch int32 with errcode.ErrCode for each available helpers in the library
• implements func (xxx) GRPCStatus() *status.Status that transforms an errcode.ErrCode to a gRPC status with some attached details
• update existing tests

---

Looks stable enough:

$ go test ./pkg/errcode/ -count 1000
ok      berty.tech/berty/v2/go/pkg/errcode      1.129s

[codecov]

Codecov Report

Merging #2176 into master will decrease coverage by 0.18%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2176      +/-   ##
==========================================
- Coverage   54.75%   54.56%   -0.19%     
==========================================
  Files          55       55              
  Lines        4630     4644      +14     
==========================================
- Hits         2535     2534       -1     
- Misses       1618     1626       +8     
- Partials      477      484       +7     

Flag	Coverage Δ
#unittests	54.56% <100.00%> (-0.19%)	⬇️

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

Impacted Files	Coverage Δ
go/framework/bertybridge/bridge_protocol.go	36.63% <ø> (ø)
go/pkg/bertyprotocol/testing.go	85.93% <ø> (ø)
go/pkg/errcode/error.go	93.44% <100.00%> (+1.95%)	⬆️
go/pkg/bertyprotocol/keystore_device.go	66.39% <0.00%> (-4.92%)	⬇️
go/pkg/bertyprotocol/keystore_message.go	54.81% <0.00%> (-1.49%)	⬇️
go/pkg/bertyprotocol/group.go	67.44% <0.00%> (-1.40%)	⬇️
go/pkg/bertyprotocol/store_metadata.go	61.89% <0.00%> (-0.45%)	⬇️

---

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[github-actions]

Expected release notes (by @moul-bot)

features:
rich gRPC errors (73c35f5)

• I hereby acknowledge these release notes are 🥙 AWESOME 🥙

[github-actions]

🎉 This PR is included in version 2.115.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀