style(RingTheory/PowerSeries/Derivative): prove derivative_pow from Derivation.leibniz_pow

[bustercopley]

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Firstly prove derivative_pow from the more general Derivation.leibniz_pow (because I think this is more illuminating), and secondly generalize derivative_pow to CommSemiring. The two are independent, in that the texts of the original and modified proofs both work fine, with either hypothesis.

[github-actions]

PR summary 1b24137ae8

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

No declarations were harmed in the making of this PR! 🐙

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).

[github-actions]

✅ PR Title Formatted Correctly

The title of this PR has been updated to match our commit style conventions.
Thank you!

[bustercopley]

easy

The proof simp [Derivation.leibniz_pow, mul_assoc] also works.

(Without intending any disrespect whatever, one could argue that the theorem is redundant with Derivative.leibniz_pow and should be deleted.)