Fix inverted FlatList RefreshControl indicator appearing at visual bottom (#17553)

[kulkarni-rohan]

Fixes #17553

Summary

Problem: FlatList with inverted={true} is used for chat/terminal UIs. It applies transform: [{scaleY: -1}] to the ScrollView and re-flips cells. RefreshControl is a child of inverted ScrollView, so it appears at physical top = visual bottom, while users expect it at visual top.

Root cause: _defaultRenderScrollComponent in VirtualizedList.js passed progressViewOffset without accounting for inversion.

Fix (JS-only, 21 lines, no new API):

• Auto-calculate progressViewOffset = visibleLength when isInvertedVirtualizedList && props.progressViewOffset==null && visibleLength>0
• Android SwipeRefreshLayout uses offset to move indicator to visual top (physical bottom = visual top after scaleY:-1)
• Clone custom refreshControl with offset when needed – improvement over Fix inverted FlatList RefreshControl indicator position #55464 which ignored custom case
• Guards visibleLength>0 to avoid flicker before layout

Supersedes #55464 (stalled, CI failing) with custom-control hardening.

Changelog:

[General] [Fixed] - Fix inverted FlatList RefreshControl indicator appearing at visual bottom instead of visual top (#17553)

Test Plan

yarn jest packages/virtualized-lists/Lists/__tests__/VirtualizedList-test.js --no-coverage --no-watchman
# 87 passed, 1 skipped, 59 snapshots (5 new tests)
# - sets progressViewOffset when inverted and layout known
# - does not set when not inverted
# - respects user-provided offset
# - does not set before layout (visibleLength=0 guard)
# - clones custom refreshControl with offset

yarn lint packages/virtualized-lists/Lists/VirtualizedList.js
# pass

Risks

Low – only affects inverted lists with onRefresh. Non-inverted unchanged. Snapshots still pass.

Known Limitation

Pull gesture still triggers at physical top (visual bottom) because native UIRefreshControl/SwipeRefreshLayout edge is at offset 0. This PR fixes indicator position (main bug title). Full gesture inversion needs native change, tracked separately.

Fixes #17553