Werk #11375: oracle_performance: Optionally new statistics for IO and system wait

With this change, new statistics for IO and system waits are added optionally. These statistics need to be activated through the rule "Oracle performance discovery". They are not automatically available since the activation of these statistics may produce a lot of additional metric data. So this data will created only, if you decide so.

To use the feature, you need to replace the agent plugin with the newest version and activate the new services through the mentioned ruleset above. You will be able to add up to three new services:

LI:oracle_performance.iostat_ios: IO statistics displayed as raw IOs. LI:oracle_performance.iostat_bytes: IO statistics displayed in bytes. LI:oracle_performance.waitclasses: Details about the reasons the DB spends time waiting.

Important: As fetching statistics about IOs may take a long time in some configurations, these data is fetched through the agent plugin asynchronously by default with section name iostats. If you change this section to synchronously, which is recommended in most cases, please check if you are able to optimize you indexing if needed to avoid such problems.

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