feat(Algebra/Polynomial/Lifts): Add mem_lifts_and_support_eq

[justus-springer]

mem_lifts_and_degree_eq was already proving the more general statement, so I extracted the proof. I need this for #34877.

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[github-actions]

PR summary a3446d5c20

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

+ exists_degree_eq_of_mem_lifts
+ exists_support_eq_of_mem_lifts

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).

[tb65536]

This name is also a bit funny. Maybe something like "exists_support_eq_of_mem_lifts"?

[justus-springer]

Sounds good, I'll also rename the other to exists_degree_eq_of_mem_lifts