fix: validate path is safe for creates

[dcshzj]

Problem

Closes ISOM-2122 (GTA-80-007 WP2).

Solution

Breaking Changes

• Yes - this PR contains breaking changes
• No - this PR is backwards compatible with ALL of the following feature flags in this doc

Bug Fixes:

• Validate path is safe before proceeding to create/rename.

Tests

• Follow the PoC provided inside the Linear ticket to ensure that it no longer works.
• Verify that you are able to create a new resource directory.
• Verify that you are able to create a new resource page.
• Verify that you are able to create a new page within a subfolder (subcollection).

[linear]

ISOM-2122 GTA-80-007 WP2: Path traversals via resource rooms & sub-collections (Misc/Medium)