Fix tag list in gcs backend

[evelynl94]

seeing this

{
  "name": "kraken/test",
  "tags": [
    "link",
    "link",
    "link",
    "link",
    "link",
    "link",
    "link"
  ]
}

we are missing c.pather.NameFromBlobPath(b) after list from gcs.

Also created #198 to follow up.

[codecov-io]

Codecov Report

Merging #197 into master will increase coverage by 0.03%.
The diff coverage is 61.53%.

@@            Coverage Diff             @@
##           master     #197      +/-   ##
==========================================
+ Coverage   66.52%   66.56%   +0.03%     
==========================================
  Files         183      183              
  Lines        9049     9056       +7     
==========================================
+ Hits         6020     6028       +8     
+ Misses       2254     2252       -2     
- Partials      775      776       +1

Impacted Files	Coverage Δ
lib/backend/gcsbackend/client.go	41.91% <61.53%> (+3.15%)	⬆️
core/peer_info.go	88.88% <0%> (+5.55%)	⬆️

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