Adds support for customising which buttons are visible on Forms and Modals

[Badgerati]

Description of the Change

• Adds a new -ButtonType parameter onto New-PodeWebForm and New-PodeWebModal, to allow full control over which buttons are visible.
• Removes -ShowReset on New-PodeWebForm.
• The default ButtonType for a Form is "Submit".
• The default ButtonType for a Modal is "Close" if no scritpblock is supplied, or "Submit" & "Close" if one is supplied.

Examples

• Form

  
  # default submit button:
  New-PodeWebForm -Name 'Example' -Content @() -ScriptBlock {}

if you want a Form with a Submit and Reset button:

New-PodeWebForm -Name 'Example' -ButtonType Submit, Reset -Content @() -ScriptBlock {}

if you want a Form with just a Reset button:

New-PodeWebForm -Name 'Example' -ButtonType Submit, Reset -Content @() -ScriptBlock {}

if you want a Form with no buttons:

New-PodeWebForm -Name 'Example' -ButtonType None -Content @() -ScriptBlock {}

* Modal
```powershell
# default close and no scriptblock
New-PodeWebModal -Name 'Example' -Content @()

# default close/submit and scriptblock
New-PodeWebModal -Name 'Example' -AsForm -Content @() -ScriptBlock {}

# scriptblock with only submit and reset
New-PodeWebModal -Name 'Example' -ButtonType Submit, Reset -AsForm -Content @() -ScriptBlock {}

# scriptblock with no buttons
New-PodeWebModal -Name 'Example' -ButtonType None -AsForm -Content @() -ScriptBlock {}