Allow changes to referral fee percentage on the implementation

[spengrah]

This PR allows the referrer to update the referral fee percentage. The change is made to the implementation contract state, and is only applied to module instances deployed after the change. Referral fee percentage for instances deployed prior to the change will not change.

[github-actions]

Changes to gas cost

Generated at commit: 7e9c266aba99f209e69db94fcd49ef974279f476, compared to commit: f7259a5d2e7e19d1d67cf643b4cd86e7c6ae41e8

🧾 Summary (10% most significant diffs)

Contract	Method	Avg (+/-)	%
DeployInstance	prepare run	-6,347 ✅ +20,847 ❌	-4.07% +1.64%

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Full diff report 👇

Contract	Deployment Cost (+/-)	Method	Min (+/-)	%	Avg (+/-)	%	Median (+/-)	%	Max (+/-)	%	# Calls (+/-)
DeployInstance	1,219,803 (-18,020)	prepare run	50,358 (-105,751) 1,276,125 (+3,900)	-67.74% +0.31%	149,762 (-6,347) 1,293,072 (+20,847)	-4.07% +1.64%	150,658 (-5,451) 1,293,225 (+21,000)	-3.49% +1.65%	150,658 (-5,451) 1,293,225 (+21,000)	-3.49% +1.65%	112 (+96) 112 (+96)

[gershido]

LGTM!