feat(LinearAlgebra/Projection): add results about inverse of Submodule.prodEquivOfIsCompl

[PSchwahn]

Add two theorems Submodule.prodEquivOfIsCompl_symm_apply and Submodule.prodEquivOfIsCompl_symm_add, which are API for Submodule.prodEquivOfIsCompl.

We believe these theorems are useful; for example, we have used their statements in a classification formalization project.

I am not sure whether the prodEquivOfIsCompl_symm_apply theorem should be tagged with @[simp]; this might lead to confluence issues. Opinions are welcome!

Co-authored by:

• Viviana del Barco
• Gustavo Infanti
• Exequiel Rivas

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[github-actions]

PR summary 2e9119ae9e

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

+ prodEquivOfIsCompl_symm_add
+ prodEquivOfIsCompl_symm_apply

You can run this locally as follows

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

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

The doc-module for script/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/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).