Refactor user-media access rules for surveys

[gino-m]

Fixes #1373

@rfontanarosa PTAL?

[gemini-code-assist]

Summary of Changes

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This pull request significantly enhances the security posture of user-media storage by replacing a broad authenticated access rule with a more precise, role-based access control system. The changes ensure that users can only access or modify media if they have the appropriate permissions for the associated survey, thereby preventing unauthorized data exposure or manipulation.

Highlights

• Granular Access Control for User Media: Implemented fine-grained access rules for user-media storage based on survey permissions, moving away from a general authenticated user access.
• New Helper Functions for Survey Access: Introduced several new functions (getSurvey, isUnlistedOrPublic, isOneOf, canViewSurvey, canCollectData) within the Firebase Storage rules to encapsulate complex survey-specific access logic.
• Dynamic Path Matching for Survey ID: Modified the /user-media storage path to include surveyId, allowing rules to dynamically fetch and evaluate survey-specific permissions.
• Segregated Read/Write Permissions: Separated read and create/write permissions for user media, applying canViewSurvey for read access and canCollectData for create/write operations.

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[gemini-code-assist]

Code Review

This pull request significantly refactors the Firebase Storage security rules for /user-media paths. It introduces fine-grained access control by adding several helper functions (getSurvey, isUnlistedOrPublic, isOneOf, canViewSurvey, canCollectData) to determine user permissions based on survey roles and visibility. Previously, any authenticated user could read and write to /user-media; now, the path includes a surveyId, and access is restricted: read access requires the user to be able to view the specific survey, and create/write access requires the user to be able to collect data for that survey. This change addresses a previous TODO to implement more specific permission-based access.