feat: fine uniformity

[plp127]

Adds the fine uniformity, and proves some properties.

---

• depends on: feat(Topology): Completely Regular Spaces are Uniformizable #24096 for showing the induced topology is equal on completely regular spaces

[github-actions]

PR summary d437923378

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.Topology.UniformSpace.Uniformizable (new file)	1487
Mathlib.Topology.UniformSpace.FineUniformity (new file)	1488

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Declarations diff

+ CompletelyRegularSpace.exists_uniformity
+ fineUniformity
+ fineUniformity_discrete
+ fineUniformity_iSup
+ fineUniformity_iSup₂
+ fineUniformity_le_iff
+ fineUniformity_mono
+ fineUniformity_sSup
+ fineUniformity_sup
+ fineUniformity_top
+ gc_fineUniformity
+ monotone_fineUniformity
+ toTopologicalSpace_fineUniformity_eq
+ uniformContinuous_fineUniformity_fineUniformity
+ uniformContinuous_fineUniformity_iff

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.

---

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).

[mathlib4-dependent-issues-bot]

This PR/issue depends on:

• feat(Topology): Completely Regular Spaces are Uniformizable #24096
  By Dependent Issues (🤖). Happy coding!