v1.6.26 - Rollup Grouping support, FIRST/LAST/MOST/AVERAGE bugfixes

[jamessimone]

• Adds new RollupGrouping__mdt, which at the moment has no fields on it. I am considering the promotion of Rollup__mdt.RollupOperation__c to a global value set in the future, which would allow for fun possibilities like taking the max of two sums. When two or more children Rollup__mdt records have their Rollup Grouping lookup field set and they are properly pointed to the same parent field, all children records will be retrieved and accounted for prior to setting the parent rollup field
• Fixes #589 by updating the rollup calculators for AVERAGE, FIRST, LAST, and MOST, all of which weren't able to handle parents with more than 50k children during batch full recalcs
• Releases an updated version of the Extra Code Coverage plugin

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 98.64865% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 96.64%. Comparing base (aebf83b) to head (dcf77cb).

:exclamation: Current head dcf77cb differs from pull request most recent head eada786

Please upload reports for the commit eada786 to get more accurate results.

Files	Patch %	Lines
rollup/core/classes/RollupState.cls	93.93%	2 Missing :warning:
rollup/core/classes/RollupAsyncProcessor.cls	98.91%	1 Missing :warning:
rollup/core/classes/RollupCalculator.cls	99.25%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #592 +/- ## ========================================== + Coverage 96.61% 96.64% +0.02% ========================================== Files 32 33 +1 Lines 6705 6821 +116 Branches 61 61 ========================================== + Hits 6478 6592 +114 - Misses 222 224 +2 Partials 5 5 ``` | [Flag](https://app.codecov.io/gh/jamessimone/apex-rollup/pull/592/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=James+Simone) | Coverage Δ | | |---|---|---| | [Apex](https://app.codecov.io/gh/jamessimone/apex-rollup/pull/592/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=James+Simone) | `96.87% <98.64%> (+0.02%)` | :arrow_up: | | [LWC](https://app.codecov.io/gh/jamessimone/apex-rollup/pull/592/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=James+Simone) | `92.02% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=James+Simone#carryforward-flags-in-the-pull-request-comment) to find out more.

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