[Merged by Bors] - chore(AdicCompletion): generalise algebra instance to separate rings

[YaelDillies]

In the existing instance Algebra R (AdicCompletion I R), R appears three times: On the left, on the right, and in I : Ideal R. The left occurrence can be generalised to a ring S such that R is a S-algebra.

Closes ImperialCollegeLondon/FLT/issues/230.

From FLT

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[github-actions]

PR summary bf5de9cbbb

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

+ instIsCentralScalar
+ instIsScalarTower
+ instSMul
+ instSMulCommClass
+ instance [Algebra S R] : Algebra S (AdicCompletion I R)
+ instance [Semiring S] [SMul S R] [Module S M] [IsScalarTower S R M] :
+ val_add_apply
+ val_neg
+ val_neg_apply
+ val_smul_apply
+ val_sub_apply
+ val_sum_apply
+ val_zero_apply
- instance : Algebra R (AdicCompletion I R)
- instance : Module R (AdicCompletion I M)
- instance : SMul R (AdicCompletion I M)
- instance : SMul ℕ (AdicCompletion I M)
- instance : SMul ℤ (AdicCompletion I M)

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.

---

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).

[eric-wieser]

bors d+

Thanks!

[mathlib-bors]

✌️ YaelDillies can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[YaelDillies]

bors merge

[mathlib-bors]

Pull request successfully merged into master.

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