Do not attempt to set breakpoints on files extensions other than .ps1 or .psm1

[rkeithhill]

Got this while trying to debug a PS script in the PowerShell repo where I had previously been debugging some C# code. So I had a mix of .cs and .ps1 breakpoints. I noticed this in my log file:

11/4/2017 1:10:59 PM [VERBOSE] - Method "ExecuteCommand" at line 491 of C:\projects\powershelleditorservices\src\PowerShellEditorServices\Session\PowerShellContext.cs

    Attempting to execute command(s):
    
        Microsoft.PowerShell.Utility\Set-PSBreakpoint
    

11/4/2017 1:10:59 PM [VERBOSE] - Method "OnSessionStateChanged" at line 1138 of C:\projects\powershelleditorservices\src\PowerShellEditorServices\Session\PowerShellContext.cs

    Session state changed --
    
        Old state: Running
        New state: Ready
        Result: Completed

11/4/2017 1:10:59 PM [ERROR] - Method "ExecuteCommand" at line 545 of C:\projects\powershelleditorservices\src\PowerShellEditorServices\Session\PowerShellContext.cs

    Execution completed with errors:
    
    A parameter cannot be found that matches parameter name 'StringBuilder'.
    A parameter cannot be found that matches parameter name 'StringBuilder'.
    A parameter cannot be found that matches parameter name 'StringBuilder'.
    A parameter cannot be found that matches parameter name 'StringBuilder'.
    Cannot set breakpoint on file 'C:\Users\Keith\GitHub\rkeithhill\PowerShell\src\System.Management.Automation\engine\parser\tokenizer.cs'; only *.ps1 and *.psm1 files are valid.
    A parameter cannot be found that matches parameter name 'StringBuilder'.
    

11/4/2017 1:10:59 PM [VERBOSE] - Method "OnSessionStateChanged" at line 1138 of C:\projects\powershelleditorservices\src\PowerShellEditorServices\Session\PowerShellContext.cs

Seems pretty obvious that we shouldn't bother to set PowerShell breakpoints on these other file types.