docs(parser): highlight JSONStringify helper

[dreamorosi]

Summary

Changes

Please provide a summary of what's being changed

This PR updates the docs for the Parser utility to better highlight the JSONStrinfied helper we added a few releases ago. Based on customers opening issues to ask for the same functionality, I assume it's hard to discover in the docs.

The PR breaks down the utility into its own section giving it a header in the navbar (see image below) and also adds the file to the API docs (this was a mistake on our side).

The PR also slightly updates the API docs description and adds a code sample for API Gateway, since it's arguably the most common case where customers might want to use this.

Please add the issue number below, if no issue is present the PR might get blocked and not be reviewed

Issue number: closes #3154

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud