Add IGraphAlg dispatch for connectivity algorithms

[nenadilic84]

Summary

Adds IGraphAlg dispatch methods for four commonly-used graph algorithms, allowing users to leverage the igraph C library's implementations via the same API pattern as the existing diameter/radius/has_isomorph dispatches.

New dispatches

Function	igraph C function	Return type
connected_components(g, IGraphAlg())	igraph_connected_components	Vector{Vector{Int}}
is_connected(g, IGraphAlg())	igraph_is_connected	Bool
articulation(g, IGraphAlg())	igraph_articulation_points	Vector{Int}
bridges(g, IGraphAlg())	igraph_bridges	Vector{SimpleEdge}

All methods accept any AbstractGraph and convert to IGraph internally. Return types match the Graphs.jl conventions.

Tests

Each new dispatch is tested against the Graphs.jl reference implementation on path graphs, cycle graphs, and disconnected graphs. All 281 tests pass.

Motivation

This addresses part of JuliaGraphs/Graphs.jl#446: "Dispatch from operations defined in Graphs to igraph implementation."

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 5.95%. Comparing base (d37f19c) to head (e5bb5b3).
⚠️ Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master     #36      +/-   ##
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+ Coverage    5.29%   5.95%   +0.66%     
=========================================
  Files           8       8              
  Lines        4310    4330      +20     
=========================================
+ Hits          228     258      +30     
+ Misses       4082    4072      -10     

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[nenadilic84]

Added CHANGELOG.md entry in the latest push.

Note: several CI checks fail on this PR but they are all pre-existing issues unrelated to this PR's changes:

• Documentation: docs/make.jl does not exist in the repo yet
• Spell Check: .typos.toml config file is missing from the repo
• evaluate: SnoopCompile FieldError on Core.Binding (tooling compatibility issue)
• performance-tracking: BenchmarkCI JSON parse error
• Julia alpha: JET incompatible with Julia 1.13 beta

All actual test jobs pass on all platforms and on Julia 1.10.

[Krastanov]

There were a few other PRs by you on projects for which we have bounties. Some of them have received full or partial reviews over the last few month or two without a follow up from you. Of course, as a volunteer you do not owe us anything, and we are always grateful when someone contributes to our packages. However, given the lack of response, and the fact that the PRs seem to have been generated by an LLM, reviewing more of these PRs creates a very significant burden on the reviewers. Thus, I will proceed to close this PR.

It is certainly possible you just happen to be too busy to respond to those PR comments right now. If that is the case, please feel free to reopen PRs you would like to pursue whenever you find some free time -- humans jumping on board to help is always appreciated.