Remove Client eventStream

[humdrum]

What this PR does / why we need it:

• Remove Client.subscribe yorkie-js-sdk#789
• change the default subscription to receive every event.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Additional documentation:

Checklist:

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

Attention: Patch coverage is 21.91781% with 57 lines in your changes are missing coverage. Please review.

Project coverage is 40.92%. Comparing base (bacbf9c) to head (c2fd5d1).

Files	Patch %	Lines
Tests/Integration/ClientIntegrationTests.swift	0.00%	25 Missing ⚠️
Sources/Document/Document.swift	42.10%	22 Missing ⚠️
Sources/Core/Client.swift	0.00%	7 Missing ⚠️
Sources/Document/DocEvent.swift	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #164      +/-   ##
==========================================
- Coverage   40.95%   40.92%   -0.03%     
==========================================
  Files         105      104       -1     
  Lines       17936    17946      +10     
==========================================
  Hits         7345     7345              
- Misses      10591    10601      +10     

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