Prevent usage of . in JsonObject key

[7hong13]

What this PR does / why we need it?

• I added a restriction on JsonObject key not to contain the delimiter ..
• getValueByPath() was not functioning correctly, so I fixed it.

Any background context you want to provide?

What are the relevant tickets?

related to yorkie-team/yorkie-js-sdk#569, yorkie-team/yorkie-ios-sdk#86

Fixes #

Checklist

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

[7hong13]

It seems like the Github Action for instrumentation tests is not working well.
I haven't found a solution yet, but I'm investigating the issue.

[hackerwins]

@7hong13 Currently, the protocol is changed in the main branch to introduce document/presence batch and that seems to be the cause of the failure.

yorkie-team/yorkie#582

How about fixing the server version to v0.4.4 until starting v0.4.5?

https://github.com/yorkie-team/yorkie-android-sdk/blob/main/docker/docker-compose.yml#L25

[codecov]

Codecov Report

Merging #124 (48a3b94) into main (3f7ddb9) will increase coverage by 0.30%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main     #124      +/-   ##
============================================
+ Coverage     77.66%   77.97%   +0.30%     
- Complexity      722      728       +6     
============================================
  Files            62       62              
  Lines          3627     3632       +5     
  Branches        536      537       +1     
============================================
+ Hits           2817     2832      +15     
+ Misses          512      502      -10     
  Partials        298      298              

Impacted Files	Coverage Δ
...ie/src/main/kotlin/dev/yorkie/document/Document.kt	83.94% <100.00%> (+7.07%)	⬆️
...main/kotlin/dev/yorkie/document/json/JsonObject.kt	91.35% <100.00%> (+1.48%)	⬆️