[analytics] add DevToolsQueryParams.isVsCode

[pq]

Part of #9811. (I'm pretty unfamiliar with this codebase so I leaned hard on Claude. I spent some time thinking it through but do let me know if I'm headed in the wrong direction!)

Ok, so... this, adds DevToolsQueryParams.isVsCode (dashTool == 'vscode-plugins' || ide == 'VSCode') and uses it in place of ide == 'VSCode' checks for:

• the survey IDE filter
• the WASM → JS fallback notification
• the Property Editor docs link

This keeps VS Code–based editors that pass dashTool (and not ide) from being treated as CLI or Android Studio.

Follow-ups (tracked in #9811): IntelliJ survey mapping via dashTool and analytics support for dashTool/dashIdeName.

There are no user-visible changes so I applied release-notes-not-required. (Yell if this is incorrect!)

(Fixes: https://github.com/flutter/dash-devexp-internal/issues/95)

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[gemini-code-assist]

Code Review

This pull request adds support for detecting VS Code based editors using the new 'dashTool' query parameter in addition to the legacy 'ide' parameter. It updates query parameter parsing, survey environment matching, preference checks, and documentation links to use the new 'isVsCode' helper, and adds corresponding unit tests. Feedback on the changes suggests a fix in 'meetsEnvironmentRequirement' to check the resolved environment from '_currentDevEnvironment()' instead of 'ga.ideLaunched.isEmpty' to prevent bypassing the environment check when 'ga.ideLaunched' is empty but VS Code is detected.

[srawlins]

I probably should have claimed #9811 or pinged you on #10037 😛

[pq]

Ah. Yes. I think that corresponds w/ the work tracked by https://github.com/flutter/dash-devexp-internal/issues/94. Maybe?

If you want to take this bit too (tracked in https://github.com/flutter/dash-devexp-internal/issues/95), good by me!

And, thanks!