Remove apollo client

[hyochan]

Description

We'd like to migrate our project from Apollo client to relay.

Related Issues

#134

Tests

Removed all the MockedProvider.

Checklist

Before you create this PR confirms that it meets all requirements listed below by checking the relevant checkboxes ([x]). This will ensure a smooth and quick review process.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I signed the [CLA].
• Run yarn lint && yarn tsc
• Run yarn test or yarn test -u if you need to update snapshot.
• I am willing to follow-up on review comments in a timely manner.

[codecov]

Codecov Report

Merging #135 into master will decrease coverage by 0.16%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #135      +/-   ##
==========================================
- Coverage   81.51%   81.35%   -0.17%     
==========================================
  Files          37       37              
  Lines        1228     1137      -91     
  Branches      131      113      -18     
==========================================
- Hits         1001      925      -76     
+ Misses        165      155      -10     
+ Partials       62       57       -5