feat: integration by parts for stieltjes vector measures

[sgouezel]

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[mathlib-bors]

This pull request is now in draft mode. No active bors state needed cleanup.

While this PR remains draft, bors will ignore commands on this PR. Mark it ready for review before using commands like bors r+ or bors try.

[github-actions]

PR summary aac675020a

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
5 files Mathlib.MeasureTheory.Function.ConvergenceInMeasure Mathlib.MeasureTheory.Function.LpOrder Mathlib.MeasureTheory.Function.LpSpace.Basic Mathlib.MeasureTheory.Function.LpSpace.Complete Mathlib.MeasureTheory.Function.LpSpace.Indicator	1
Mathlib.MeasureTheory.Function.LpSpace.CompleteOfComplete (new file)	2250
Mathlib.MeasureTheory.VectorMeasure.WithDensityVec (new file)	2259

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Declarations diff

+ AEFinStronglyMeasurable.exists_measurableSet_measure_pos_lt_top
+ FinStronglyMeasurable.exists_measurableSet_measure_pos_lt_top
+ coeFn_const_eq'
+ compLpL₂
+ compLpL₂_apply_apply
+ compLpₗ₂
+ completeSpace_of_completeSpace_Lp
+ enorm_integral_le
+ enorm_setToFun_le
+ foo
+ integral_undef
+ integral_zero
+ norm_compLpL₂
+ norm_toL1_eq_lintegral_enorm
+ withDensity

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

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

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

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

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No changes to strong technical debt.

No changes to weak technical debt.