feat: implement get_campaign_fee_history (#95)

[EDOHWARES]

PR Summary: Track Campaign Fees Generation (#95)

Objective: Implements a persistent counter to track the total platform fees generated by individual campaigns.

Key Changes:

• Storage: Added CampaignFeeHistory to StorageKey for cross-invocation persistence.
• Logic (donate): Intercepts each new donation, calculates the assumed platform fee (currently set at a 1% model), and increments the dedicated tracker counter mapping for that specific campaign.
• 🔍 Query Function: Added get_campaign_fee_history(env, campaign_id) to allow fetching the exact amount earned from any specific campaign.
• Testing: Added test_get_campaign_fee_history which actively verifies that multiple successive donations correctly calculate, increment, and compound into the tracker variable appropriately.

Closes #95

[Akshola00]

looks good to me, thank you for your contribution