chore(Combinatorics/Graph): per def "expose" tag

[Jun2M]

Combinatorics/Graph/Basic.lean has a file-wide expose tag. This PR moves it to defs that requires them.

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[github-actions]

PR summary d2a1d69b85

Import changes exceeding 2%

%	File
+53.07%	Mathlib.Combinatorics.Graph.Basic
+52.03%	Mathlib.Combinatorics.Graph.Subgraph

Import changes for modified files

Dependency changes

File	Base Count	Head Count	Change
Mathlib.Combinatorics.Graph.Basic	488	747	+259 (+53.07%)
Mathlib.Combinatorics.Graph.Subgraph	492	748	+256 (+52.03%)
Mathlib.Topology.CWComplex.Classical.Graph	1413	1440	+27 (+1.91%)

Import changes for all files

Files	Import difference
Mathlib.Topology.CWComplex.Classical.Graph	27
3 files Mathlib.Combinatorics.Graph.Delete Mathlib.Combinatorics.Graph.Lattice Mathlib.Combinatorics.Graph.Subgraph	256
Mathlib.Combinatorics.Graph.Basic	259

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Declarations diff

+ Adj.exists
+ IsLoopAt.isLink
+ adj_iff
+ inc_iff_isLoopAt_or_isNonloopAt

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.

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).

[github-actions]

✅ PR Title Formatted Correctly

The title of this PR has been updated to match our commit style conventions.
Thank you!