Adds inbuilt support for caching values

[Badgerati]

Description of the Change

Adds inbuilt support for caching values, both via functions and a new $cache: scoped variable. The inbuilt cache stores values in-memory with a default TTL of 1hr (can be overridden), and there is also support for adding custom storage as well

The following new functions have been added:

• Get-PodeCache
• Set-PodeCache
• Test-PodeCache
• Remove-PodeCache
• Clear-PodeCache
• Add-PodeCacheStorage
• Remove-PodeCacheStorage
• Get-PodeCacheStorage
• Test-PodeCacheStorage
• Set-PodeCacheDefaultStorage
• Get-PodeCacheDefaultStorage
• Set-PodeCacheDefaultTtl
• Get-PodeCacheDefaultTtl

Related Issue

Resolves #1184

Examples

Add-PodeRoute -Method Get -Path '/' -ScriptBlock {
    # check cache
    $cpu = $cache:cpu
    if ($null -ne $cpu) {
        Write-PodeJsonResponse -Value @{ CPU = $cpu }
        return
    }
    # get cpu, and cache for 1hr
    $cache:cpu = (Get-Counter '\Processor(_Total)\% Processor Time').CounterSamples.CookedValue
    Write-PodeJsonResponse -Value @{ CPU = $cache:cpu }
}

or the same using $cache: instead:

Add-PodeRoute -Method Get -Path '/' -ScriptBlock {
    # check cache
    $cpu = $cache:cpu
    if ($null -ne $cpu) {
        Write-PodeJsonResponse -Value @{ CPU = $cpu }
        return
    }
    # get cpu, and cache for 1hr
    $cache:cpu = (Get-Counter '\Processor(_Total)\% Processor Time').CounterSamples.CookedValue
    Write-PodeJsonResponse -Value @{ CPU = $cache:cpu }
}