feat(ProbabilityTheory): add APIs for predicationPart and martingalePart

[CoolRmal]

Upstream results from RemyDegenne/brownian-motion#422

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[github-actions]

PR summary 90419b0904

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ IsPredictable.martingalePart_eq
+ IsPredictable.predictablePart_eq
+ Martingale.martingalePart_eq
+ Martingale.predictablePart_eq_zero
+ Submartingale.monotone_predictablePart
+ Submartingale.nonneg_predictablePart
+ isPredictable_predictablePart
+ martingalePart_add
+ martingalePart_smul
+ martingalePart_zero
+ predictablePart_add
+ predictablePart_add_one
+ predictablePart_smul

You can run this locally as follows

## summary with just the declaration names:
./scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).