fix(ios): handle async player access in text track selection

[tarikfp]

Fix Potential Race Condition in Video Player Text Track Selection

Description

Potentially fixed a crash that happens when text tracks get selected while the player is being destroyed. Super hard to reproduce but shows up in crash logs. Basically the player exists when we start the async operation but might be gone by the time we try to use it.

Changes

• Added weak self in async block
• Added guard check for player instance
• Made sure we have strong reference to player during async operation

Steps to Maybe Reproduce

Really hard to get this consistently, but here's what might trigger it:

1. Switch videos really fast
2. Change text tracks while video is loading
3. Background the app during text track changes

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would break existing functionality)

Screenshots

Checklist

• Code follows project style guidelines
• Edge cases tested where possible
• No new warnings introduced

[KrzysztofMoch]

LGTM, Thanks for PR!