Auto-configure AppOptics metrics

[jkschneider]

See micrometer-metrics/micrometer#419

[snicoll]

This is implemented in f161d26 but I am not keen to merge this yet until we hear from @jkschneider (in particular micrometer-metrics/micrometer#936 and micrometer-metrics/micrometer#933 and micrometer-metrics/micrometer#934)

[jkschneider]

All related issues resolved.