feat(RamificationInertia): add ramificationIdx_le_ramificationIdx and inertiaDeg_le_inertiaDeg

[xroblot]

Assume that Q is over P that is over p. We prove that:

• Ideal.ramificationIdx P Q ≤ Ideal.ramificationIdx p Q
• Ideal.inertiaDeg P Q ≤ Ideal.inertiaDeg p Q

These results follow from Ideal.ramificationIdx_algebra_tower and Ideal.inertiaDeg_algebra_tower but they are proved here in a more general situation.

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• depends on: [Merged by Bors] - chore(RamificationInertia): remove an unnecessary hypothesis in inertiaDeg_algebraMap #35483

[github-actions]

PR summary 2f9c494826

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

+ inertiaDeg_le_inertiaDeg
++ ramificationIdx_le_ramificationIdx

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 scripts/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).

[mathlib-dependent-issues]

This PR/issue depends on:

• [Merged by Bors] - chore(RamificationInertia): remove an unnecessary hypothesis in inertiaDeg_algebraMap #35483
  By Dependent Issues (🤖). Happy coding!