Undo some TODO

[skotopes]

What's new

• TODO FL-3519: documentation and link to source added
• TODO FL-3506: removed, change ownership by copy is good
• TODO FL-3505: removed, mutex alone is not going to fix issue with WPAN architecture
• TODO FL-3500: refactored, store pin numbers in GpioPinRecord, fix gpio app crash caused by incorrect gpio_pins traversal.
• TODO FL-3510: removed, comment added
• TODO FL-3515: removed, questionable but ok
• TODO FL-3498: implemented, guarding view port access with mutex.
• TODO FL-3514: removed, yes we should
• TODO FL-3497: removed, requires radically different settings approach
• TODO FL-3497: impossible to fix with current memory allocator

Verification

• Full tests, extra attention to GUI lockup and performance degradation

Checklist (For Reviewer)

• PR has description of feature/bug or link to Confluence/Jira task
• Description contains actions to verify feature/bugfix
• I've built this code, uploaded it to the device and verified feature/bugfix

[github-actions]

Compiled firmware for commit 181940c1:

• 📦 Update package
• 📥 DFU file
• ☁️ Web/App updater