feat(Topology/UniformSpace): define nonarchimedean uniformity

[pechersky]

prove basic result that such a space is topologically zero dimensional

leave todos for future directions

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[github-actions]

PR summary 4e8fc5cc1b

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.Topology.UniformSpace.Ultra (new file)	625

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Declarations diff

+ IsTransitiveRel
+ IsTransitiveRel.ball_subset_of_mem
+ IsTransitiveRel.comp_eq_of_idRel_subset
+ IsTransitiveRel.comp_subset_self
+ IsTransitiveRel.symmetrizeRel
+ IsUltraUniformity
+ IsUltraUniformity.mk_of_hasBasis
+ UniformSpace.ball_eq_of_mem_of_isSymmetricRel_of_isTransitiveRel
+ _root_.IsTransitiveRel.isOpen_ball_of_mem_uniformity
+ _root_.TopologicalSpace.isTopologicalBasis_clopens
+ isClopen_ball_of_isSymmetricRel_of_isTransitiveRel_of_mem_uniformity
+ isClosed_ball_of_isSymmetricRel_of_isTransitiveRel_of_mem_uniformity
+ isTransitiveRel_empty
+ isTransitiveRel_iff_comp_subset_self
+ isTransitiveRel_singleton
+ isTransitiveRel_univ
+ nhds_basis_clopens

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).

[pechersky]

bot fix style

[ADedecker]

Thanks a lot!