feat(Algebra): expand Subalgebra.restrictScalars API

[matthewjasper]

Add an instance for the original algebra structure, the implied scalar tower instances, and the algebra equivalence with the original subalgebra. Use this to remove some set_option backward.isDefEq.respectTransparency.

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[github-actions]

PR summary 00dbc4ec64

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

+ restrictScalars.SMul
+ restrictScalars.coe_algebraMap
+ restrictScalars.coe_smul
+ restrictScalars.isScalarTower
+ restrictScalars.isScalarTower'
+ restrictScalars.origAlgebra
+ restrictScalarsEquiv
+ restrictScalarsEquiv_apply
+ restrictScalarsEquiv_symm_apply

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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Decrease in tech debt: (relative, absolute) = (3.00, 0.00)

Current number	Change	Type
6412	-3	backward.isDefEq.respectTransparency

Current commit 988f6f43ac
Reference commit 00dbc4ec64

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).

[eric-wieser]

Can you use something like RingHom.restrict here?