feat: support item record

[zhu-xiaowei]

Description

1. support adding items with custom attributes.

NOTE: This is a breaking change, only pipelines from version 1.1+ can handle items with custom attribute.

General Checklist

• Added new tests to cover change, if needed
• Build succeeds using Swift Package Manager
• All unit tests pass
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Documentation update for the change if required
• PR title conforms to conventional commit style
• If breaking change, documentation/changelog update with migration instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov-commenter]

Codecov Report

Attention: 23 lines in your changes are missing coverage. Please review.

Comparison is base (1708b75) 95.40% compared to head (7437e0f) 94.62%.

Files	Patch %	Lines
...am/Dependency/Clickstream/Event/EventChecker.swift	90.58%	21 Missing ⚠️
...am/Support/Extension/JsonObject+ToJsonString.swift	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #38      +/-   ##
==========================================
- Coverage   95.40%   94.62%   -0.78%     
==========================================
  Files          34       35       +1     
  Lines        1784     1916     +132     
==========================================
+ Hits         1702     1813     +111     
- Misses         82      103      +21     

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