[macOS] Enable TextField borders on macOS 26

[SougandhS]

Restore visible borders for SWT text controls on macOS 26 and later to improve control visibility and readability.

Part of #3286 and eclipse-platform/eclipse.platform.ui#3885

Before [Light]

After[Light]

Before [Dark]

After [Dark]

[github-actions]

Test Results (macos)

   58 files  ±0     58 suites  ±0   6m 2s ⏱️ -6s
4 571 tests ±0  4 324 ✅ ±0  247 💤 ±0  0 ❌ ±0 
2 202 runs  ±0  2 138 ✅ ±0   64 💤 ±0  0 ❌ ±0 

Results for commit 81353d1. ± Comparison against base commit 24b4c49.

[Phillipus]

Is this PR intended to be merged after the Equinox launcher is compiled with macOS 26 SDK? This checks only the running macOS version so Text controls on macOS 26 that have SWT.BORDER style now look different:

Before this PR (correct border style):

After this PR:

[SougandhS]

This checks only the running macOS version so Text controls on macOS 26 that have SWT.BORDER style now look different:

Is there any current build agent/ binary check APIs in SWT ?

[Phillipus]

Is there any current build agent/ binary check APIs in SWT ?

Not API. I think the idea as @HeikoKlare says is to build the equinox binary on macOS SDK 26 at some point in the future.

As mentioned in #3286 the idea is to fix problems that occur when running SWT or an app that consumes SWT (Eclipse, RCP app) from a binary that has been compiled with macOS 25 SDK. Right now this seems to be only the Homebrew Java 25. Eclipse is launched with the Equinox launcher compiled with macOS 15 SDK and most Java binaries with 14 or 15.

In this issue setting the Text control's border by checking whether the running macOS is macOS 26 or later will add an additional border in all cases.