Fix debug options breaking launcher on Windows

Fixes #8100

Steps

On Windows with sbt 1.10.11, setting debug options via SBT_OPTS breaks the launcher:

set SBT_OPTS=-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=localhost:1234
sbt.bat

Problems

When the JVM debug agent starts, it prints Listening for transport dt_socket at address: 1234 to stdout. The copyrt function captures this output and tries to parse it as a file path, which fails with InvalidPathException due to the colon character.

The root cause is that the Windows batch script reads the first line of --rt-ext-dir output without any filtering:

set /p java9_ext= < "%TEMP%.\rtext.txt"

Expectations

sbt should launch normally even when debug options are set, allowing developers to attach a debugger.

Solution

I added filtering to the Windows batch script so it only picks up the line containing java9-rt-ext-, which is the actual path we care about. This matches what the Unix script already does with grep java9-rt-ext-.

for /f "tokens=*" %%a in ('findstr /c:"java9-rt-ext-" "%TEMP%.\rtext.txt"') do set "java9_ext=%%a"

Now any debug agent noise gets ignored, and only the rt.jar path is captured.

Notes

As discussed with @eed3si9n in #8100, this is a minimal fix that brings the Windows script in line with the Unix behavior. A more robust solution (using a RTJAR= prefix) could be done later if needed, but this should address the immediate issue.

Contribution by Gittensor, see my contribution statistics at https://gittensor.io/miners/details?githubId=94194147