feat(by_contra,contrapose): warn if the push_neg step does nothing

[grunweg]

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• depends on: chore(AtLocation): allow throwing a warning when no progress is being made #31597
• depends on: refactor(AtLocation): allow throwing a warning when no progress is being made #37899
• depends on: chore: avoid superfluous use of push_neg with contrapose, by_contra o… #37937
• depends on: chore(AtLocation): clean up backtick handling #37999
• depends on: feat(push): error message tweaks #38008

[github-actions]

PR summary 24bf43f6f8

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

+ BehaviorIfUnchanged

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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No changes to technical debt.

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).

[mathlib-dependent-issues]

This PR/issue depends on:

• chore(AtLocation): allow throwing a warning when no progress is being made #31597
• refactor(AtLocation): allow throwing a warning when no progress is being made #37899
• chore: avoid superfluous use of push_neg with contrapose, by_contra o… #37937
• chore(AtLocation): clean up backtick handling #37999
• feat(push): error message tweaks #38008
  By Dependent Issues (🤖). Happy coding!

[mathlib-merge-conflicts]

This pull request has conflicts, please merge master and resolve them.