Scale Table.HEADER_MARGIN by zoom level instead of using fixed pixels

[ShahzaibIbrahim]

The Table.HEADER_MARGIN constant defines the extra fixed-width spacing for table headers, while the Table.HEADER_EXTRA constant specifies the additional spacing applied to the header area. Previously, both were defined as fixed pixel values,
which worked at 100% zoom but did not scale properly on high-DPI monitors.

This change redefines HEADER_MARGIN and HEADER_EXTRA in points and converts them to pixels based on the current zoom level, ensuring consistent header spacing across different display scales.

How to Test

• Run Snippet 8 from Snippet Explorer with Primary monitor of 250%
• You will notice the width of the header wider than previous state since we take zoom into consideration.

[github-actions]

Test Results

   539 files   -  7     539 suites   - 7   35m 34s ⏱️ + 6m 9s
 4 372 tests  - 54   4 357 ✅  - 52   14 💤  - 3  0 ❌ ±0  1 🔥 +1 
16 696 runs   - 54  16 571 ✅  - 52  124 💤  - 3  0 ❌ ±0  1 🔥 +1 

For more details on these errors, see this check.

Results for commit ca5e3a8. ± Comparison against base commit d5dc661.

This pull request removes 54 tests.

AllWin32Tests ImageWin32Tests ‑ testDisposeDrawnImageBeforeRequestingTargetForOtherZoom
AllWin32Tests ImageWin32Tests ‑ testDrawImageAtDifferentZooms(boolean)[1] true
AllWin32Tests ImageWin32Tests ‑ testDrawImageAtDifferentZooms(boolean)[2] false
AllWin32Tests ImageWin32Tests ‑ testImageDataForDifferentFractionalZoomsShouldBeDifferent
AllWin32Tests ImageWin32Tests ‑ testImageShouldHaveDimesionAsPerZoomLevel
AllWin32Tests ImageWin32Tests ‑ testRetrieveImageDataAtDifferentZooms(boolean)[1] true
AllWin32Tests ImageWin32Tests ‑ testRetrieveImageDataAtDifferentZooms(boolean)[2] false
AllWin32Tests TestTreeColumn ‑ test_ColumnOrder
AllWin32Tests Test_org_eclipse_swt_dnd_DND ‑ testByteArrayTransfer
AllWin32Tests Test_org_eclipse_swt_dnd_DND ‑ testFileTransfer
…