Output Build Logs to a File for the Jenkins Warnings Plugin

[cailafinn]

Description of work

Summary of work

Added a file output in the same style as the ctest log for the build log.

Once this is merged, the configurations for the 3 PR OSs need to be changed to check this log when the Warnings plugin is run.

• https://builds.mantidproject.org/job/pull_requests-conda-linux/configure > Post-build Actions
• https://builds.mantidproject.org/job/pull_requests-conda-osx/configure > Post-build Actions
• https://builds.mantidproject.org/job/pull_requests-conda-windows/configure > Post-build Actions

Fixes #38148

Further detail of work

To test:

1. Rerun a job (or run the build script locally). There should be a .log file associated with each OS containing the log from the build step.

This does not require release notes because it is not a user-facing change.

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[thomashampson]

I can confirm that the new build log files are present and have been archived by the PR jobs.