Runtime: CRTs - variable revenue split & inflation rates

# Problem
I have issued a creator token (https://gleev.xyz/channel/24503?tab=Token) and it seems like it has a very promising trajectory (https://github.com/Joystream/atlas/issues/6271#issuecomment-2108635432) that will likely make it the 4th highest CRT in terms of revenue within the next 30 days.
(for some context: my CRT's revenue currently comes from my validator rewards so is very different to almost all other CRTs)

* The problem I have is that I chose a revenue share of 40% and this is not adjustable--I think I would've rather had a revenue split that was more equitable to my CRT holders but I didn't really do the math before creating the CRT so didn't think that much into the future--in the same spirit, even if a content creator had a CRT and -did- do the math, creator rewards are unpredictable and with no method to change the revenue split this can be a limitation.
* Due to creator rewards and CRTs being generally unpredictable, it may make a lot of sense for a creator to be able to use some "trial & error" and adjust the `revenue split %` at certain intervals. Some high revenue channels may not perform as expected and may end up as being unequitable to the creator and likewise a CRT may perform extremely well on the market and the CRT owner may wish to increase the % afforded to investors to "sweeten the deal"

# Solution
There are probably many ways that could tackle this problem, but one I can think of is:
* Change the runtime so that when triggering a revenue split, the creator can set a new revenue split that will take effect at the end of the current revenue split--it may be more productive to make this adjustment only be some increment/decrement % wise (i.e. "you can only increase or decrease your revenue split by 12.5% at a time)