Enhance Set and Add for representing nested elements

[chacha912]

What this PR does / why we need it?

When setting values for objects or arrays, we first created the outer shells of objects ({}) and arrays ([]), and then individually set the inner values. As a result, multiple operations were generated. This PR introduces a modification that allows setting initial values directly within a single operation, simplifying the process and reducing the number of generated operations.

Consider the example of setting the shape of a circle:

doc.update((root) => {
  root.shape = {};
});

doc.update((root) => {
  root.shape.circle = {
    point: { x: 0, y: 0 },
    color: 'red',
  };
});

doc.update((root) => {
  root.shape.circle = {
    point: { x: 1, y: 1 },
    color: 'blue',
  };
});

as-is

In this case, the generated operations are 1, 5, and 5, respectively. Examining the undo operations in the final state reveals that each set operation is followed by a remove operation. Finally, a set operation is performed to restore the previous state of circle = {point: { x: 0, y: 0 }, color: 'red'}. However, due to the current set operation's limitation in setting only outer shells, it results in improper behavior.

to-be

This PR enhances the set operation to handle both outer shells and inner values properly.
So it looks like the set operation is only generated once, and undo operations are applied correctly.

Any background context you want to provide?

What are the relevant tickets?

Fixes yorkie-team/yorkie#663

Checklist

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

[codecov]

Codecov Report

Attention: 15 lines in your changes are missing coverage. Please review.

Comparison is base (5b1425d) 68.01% compared to head (5f6fffe) 69.12%.

Files	Patch %	Lines
src/api/converter.ts	50.00%	4 Missing and 3 partials ⚠️
src/document/operation/remove_operation.ts	78.57%	1 Missing and 2 partials ⚠️
src/document/json/element.ts	88.23%	1 Missing and 1 partial ⚠️
src/document/operation/set_operation.ts	83.33%	0 Missing and 2 partials ⚠️
src/document/operation/add_operation.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #691      +/-   ##
==========================================
+ Coverage   68.01%   69.12%   +1.10%     
==========================================
  Files          58       58              
  Lines        8776     8787      +11     
  Branches      793      800       +7     
==========================================
+ Hits         5969     6074     +105     
+ Misses       2548     2454      -94     
  Partials      259      259              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[hackerwins]

@chacha912 Thanks for your contribution.