v3.10.0: Allocator upgrade

More details in post: The convergence of marginal ROAS in the budget allocation in Robyn

• Feat: all new one-pager for robyn_allocator() showing initial, bounded and less-bounded scenarios, using last month's worth of data by default. Relevant changes from previous versions: initial spend is now mean of date range selected, not non-zero mean anymore + deprecated "max_response_expected_spend" scenario + carryover information is now provided in the curves + inform user when budget is topped and can't be fully allocated + added mROAS / mCPA for better understanding of allocation. And one step closer to the forecast functionality. #600
• Feat: robyn_response() now requires date or date range for adstocking (last period by default) and accepts single or multiple values to return different use cases and scenarios.
• Feat: new transform_adstock() exported wrapper function.
• Feat: added NRMSE validation on test set.
• Feat: added prophet monthly component.
• Fix: issue with differences on OutputCollect$OutputModels and OutputModels to produce ts_validation plot. #596
• Fix: added correct solID for fixed hyperparameters (not 1_1_1).
• Recode: reduced the size of xDecompVec on OutputCollect to only pareto-front models.
• Recode: got rid of "ggcorrplot" and "rPref" package dependencies.
• Docs: added blueprint link to demo.R.

Full Changelog: v3.9.0...v3.10.0