[Autobuild] Add log file prompt

[jeremiahpslewis]

Supersedes https://github.com/JuliaPackaging/BinaryBuilder.jl/pull/1152

Resolves #1149

If *.log files are present, yields:

┌ Warning: Build failed, the following log files were generated:
│   - ${WORKSPACE}/srcdir/wget-1.21.1/config.log
│ 
│ Launching debug shell:
└ @ BinaryBuilder ~/.julia/dev/BinaryBuilder/src/AutoBuild.jl:822

Otherwise (in case of no log files), no change from current version.

[jeremiahpslewis]

@giordano Updated and hopefully ready to go. The file paths are also 'option-click-able' in VSCode, so you don't just see the files, it's also easy to pull up the logs while debugging.

[jeremiahpslewis]

Thank you!