Split the Handler function into multiple PowerShell functions

[Badgerati]

The handler function should be split out into multiple PowerShell functions. Each of these functions should be exported in pode.psd1.

This will also finally add support for multiple handlers.

• Adding a handler

Add-PodeSmtpHandler
    -Name <string>
    -ScriptBlock <scriptblock>
    [-FilePath <string>]

Add-PodeTcpHandler
    -Name <string>
    -ScriptBlock <scriptblock>
    [-FilePath <string>]

Add-PodeServiceHandler
    -Name <string>
    -ScriptBlock <scriptblock>
    [-FilePath <string>]

• Removing a handler

Remove-PodeSmtpRoute
    -Name <string>

Remove-PodeTcpRoute
    -Name <string>

Remove-PodeServiceRoute
    -Name <string>