feat(Topology/Homeomorph): add Equiv.IsHomeomorph_iff and LinearEquiv.IsHomeomorph_iff

[sharky564]

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This PR adds two characterisations of IsHomeomorph for bundled equivalences. For a plain Equiv between topological spaces, Equiv.isHomeomorph_iff states that the equivalence is a homeomorphism if and only if it is continuous in both directions. The corresponding statement for a LinearEquiv between topological modules is added as LinearEquiv.isHomeomorph_iff, derived from the Equiv version.
The motivation comes from work on topological complements of submodules in PR #38547, where one wants to upgrade a LinearEquiv to a ContinuousLinearEquiv and the cleanest characterisation is in terms of continuity in both directions. The existing API offers isHomeomorph_iff_exists_inverse, but for equivalences this requires manually identifying the existential inverse with e.symm, which is unnecessarily indirect.

[github-actions]

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[github-actions]

PR summary b9cac30121

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

+ Equiv.isHomeomorph_iff
+ LinearEquiv.isHomeomorph_iff

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

## summary with just the declaration names:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

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No changes to technical debt.

This script lives in the mathlib-ci repository. To run it locally, from your mathlib4 directory:

git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci
../mathlib-ci/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).