feat: Seek firmware from path specified in kernel parameter path filesystem

[yejseo01]

Changes

• Documentation change on root-dir so that /lib/firmware is not assumed by the users
• Test changes to check the firmware directory based on what is inside /sys/module/firmware_class/parameters/path
• Change e2e test to create firmware based on readings of /sys/module/firmware_class/parameters/path
• Update the filesystem manager to keep the /sys/module/firmware_class/parameters/path and the actual firmware path
• Verify firmware's existence based on the path pointed by /sys/module/firmware_class/parameters/path
• Add helper file mkfile() which would make all the parent folder of a path and make a file with the basename of the path

Checklist

• 🤖 This change is covered by tests as required.
• 🤹 All required manual testing has been performed.
• 📖 All documentation updates are complete.

[Copilot]

Pull Request Overview

This PR updates the firmware loading mechanism to read the firmware directory path from /sys/module/firmware_class/parameters/path instead of hardcoding /lib/firmware. This makes the simulator more flexible and aligned with how Linux actually determines firmware locations.

Key changes:

• Modified FileSystemManager to track and create the firmware path configuration file
• Updated tests to dynamically read firmware directory from the system parameter file
• Added mkfile() helper to create parent directories and files atomically

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
pkg/simulator/filesystem.go	Added firmware path file tracking, mkfile() helper, and verification logic to read firmware directory from system parameters
e2e/running_firmware_test.go	Updated test to read firmware directory from system parameter file instead of hardcoded path
e2e/boostrapping_test.go	Modified bootstrapping test to verify firmware directory based on system parameter file
cmd/remoteproc-simulator/main.go	Updated documentation to remove assumption about /lib directory creation

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[Luke-Parkin]

Happy with this.

I am a bit concerned about us making files in the real /sys/ (which appears to be the default state) but this is probably something for another ticket/pr.