feat(fs): implement RLIMIT_FSIZE limit checking

[fslongjin]

• Add file size limit checking before write operations
• Send SIGXFSZ signal when exceeding file size limit
• Handle partial writes when approaching the limit
• Add check for O_PATH file descriptors in writeable method
• Update test configurations for write limit tests

[Copilot]

Pull Request Overview

This PR implements RLIMIT_FSIZE (file size limit) checking in the filesystem layer to enforce maximum file sizes and handle limit violations according to POSIX standards.

• Adds file size limit validation before write operations with SIGXFSZ signal handling
• Implements partial write support when approaching file size limits
• Enhances file descriptor validation to reject O_PATH descriptors for write operations

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
user/apps/tests/syscall/gvisor/whitelist.txt	Enables write_test in the gvisor test suite
user/apps/tests/syscall/gvisor/blocklists/write_test	Adds blocklist for write tests that fail due to missing system calls
kernel/src/process/mod.rs	Sets default RLIMIT_FSIZE value to unlimited (u64::MAX)
kernel/src/filesystem/vfs/file.rs	Implements RLIMIT_FSIZE checking in write operations and O_PATH validation

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}