Add IfExists parameter for Routes to define if a second Route should Error, Overwrite or be Skipped

[Badgerati]

Description of the Change

Adds a new -IfExists parameter to Add-PodeRoute, Add-PodeStaticRoute, and Add-PodeSignalRoute - including the relevant Group functions like Add-PodeRouteGroup. This parameter takes the values Default, Error, Overwrite, and Skip. (the default behaviour is Error, as it currently is)

The same parameter has also been added onto Use-PodeRoutes, meaning you can apply Skip to all Routes on mass:

Use-PodeRoutes -IfExists Skip

Furthermore, there's also a new Set-PodeRouteIfExistsPreference function which let's you overwrite the global default behaviour of Error:

Set-PodeRouteIfExistsPreference -Value Overwrite

In the case of the options:

• Default: will use the IfExists value from higher up the hierarchy (see below) - if none defined, Error is the final default
• Error: if the Route already exists, throw an error
• Overwrite: if the Route already exists, delete the existing Route and recreate with the new definition
• Skip: if the Route already exists, skip over the Route and do nothing

The default value that is used is defined by the following hierarchy:

• IfExists value of the current Route (like Add-PodeRoute)
• IfExists value of the Route Group (like Add-PodeRouteGroup)
• IfExists value from Use-PodeRoute
• IfExists value from Set-PodeRouteIfExistsPreference
• Throw an Error

This also adds 3 new Test functions:

• Test-PodeRoute
• Test-PodeStaticRoute
• Test-PodeSignalRoute

Related Issue

Resolves #964

Examples

To Skip over creating a Route that already exists:

Start-PodeServer -Thread 2 -Verbose {
    Add-PodeEndpoint -Address * -Port 8090 -Protocol Http

    Add-PodeRoute -Method Get -Path '/' -ScriptBlock {
        Write-PodeJsonResponse -Value @{ Result = 1 }
    }

    Add-PodeRoute -Method Get -Path '/' -IfExists Skip -ScriptBlock {
        Write-PodeJsonResponse -Value @{ Result = 2 }
    }
}

Running the above, and calling http://localhost:8090/ will return the result of 1 not 2 😄. If you swap Skip to Overwrite and re-run, you'll get the result of 2 instead!