Experimental: Adds code caching for faster framework loading

[LordHepipud]

Current Situation

Currently the entire Framework is taking a huge amount of time to load the files. This causes several issues:

• Slow loading increases the runtime of checks
• High CPU usage for the initial loading of the Framework
• High CPU usage over a longer period of time, cause more impcact on the systems

Possible solutions

Add caching

To reduce the impact for the Framework loading, we could add a cache file containing all Cmdlets, Enums and Functions allowing us to import file on initialization instead of having of to search for all .psm1 files and load them one by one

Use Nested Modules for PowerShell Plugins

PowerShell plugins right now are using Use-IcingaPlugins which searchs for all .psm1 files inside the plugin folder to load them. We should use NestedModules here, as the overall impact is lower. On Framework side we can't do this how ever without loading times to explode. Plugins are tracked at issue #87 here

Current Status

Mitigated

Usage

You can enable/disable this feature by using Enable-IcingaFrameworkCodeCache and Disable-IcingaFrameworkCodeCache. Updating the cache is done with Write-IcingaFrameworkCodeCache

Issue reference: #131

[LordHepipud]

Without caching:

With caching:

Still not perfect but the performance is a lot better and the system itself feels smoother