BUG: Make preflight geometry import metadata-only

[joeykleingers]

Summary

During a metadata-only preflight, DataStructureReader now leaves geometry connectivity — vertex/face/edge lists, derived connectivity, and rectilinear-grid bounds — as an EmptyDataStore carrying only shape and type (exactly like ordinary attribute arrays), instead of eagerly bulk-reading it from disk. This removes a wasted per-geometry disk read from every preflight, which is costly on high-latency storage such as network mounts. Execute is unchanged — it imports the real connectivity stores directly in readGroup.

• readGroup already imports every array as an EmptyDataStore when useEmptyDataStores is set, so loadRequiredData is now skipped during preflight.
• Geometry IO readers (EdgeGeomIO, INodeGeom0d/1d/2d/3dIO, RectGridGeomIO) no longer register connectivity as required data — those ids were only ever consumed by the eager preflight read.
• Forward useEmptyDataStores from the std::filesystem::path overload of DataStructureReader::ReadFile to the FileIO overload; it was previously dropped and always defaulted to false.

Test Plan

• DREAM3DFileTest passes (adds preflight metadata-only coverage asserting geometry connectivity stores are empty after preflight and populated after execute)
• Existing DREAM3D read/write and geometry tests pass

[imikejackson]

I pushed a3fcfc7 to this branch after reviewing — two things, no change to the approach:

• Removed the now-dead required-data machinery from DataStructureReader. With the geometry IO readers no longer registering connectivity ids, nothing calls addRequiredId/addRequiredPath anymore, so loadRequiredData was a guaranteed no-op in every code path — including the !useEmptyDataStores call this PR kept, which implied the pass still mattered for full reads. Deleted addRequiredPath, both addRequiredId overloads, loadRequiredData, and the m_RequiredPaths/m_RequiredIds members. The static FinishImportingObject stays; Dream3dIO uses it for the per-path execute import.

• Broadened the new test to cover every reader this PR touched. It previously only exercised TriangleGeometry (INodeGeom2dIO); it's now table-driven over geoms.dream3d's edge, triangle, quad, tetrahedral, and hexahedral geometries plus the rect-grid X/Y/Z bounds, with a DYNAMIC_SECTION per connectivity array in all three blocks (preflight, execute, ReadFile path overload).

Also chased the two riskiest paths and found no regressions: no preflightImpl in simplnx or downstream plugins reads connectivity values (only shape/type, which EmptyDataStore preserves — value access throws loudly), and execute through ImportH5ObjectPathsAction is unaffected because connectivity arrays are ordinary paths in m_Paths and get their real stores from DataArrayIO::finishImportingData.

Verified on both builds: full SimplnxCore + core-library suites pass 100% on in-core (simplnx-Rel) and out-of-core (simplnx-ooc-Rel).