Add slash command macro functions

[cwisniew]

Identify the Bug or Feature request

resolves #1691

Description of the Change

Adds the following macro functions
Set an alias

[slash.setAlias("alias", "command")]

Returns a JSON Object withe the defined aliases (defined by macro or /alias)

[slash.getAliases()]

Clears an alias

[slash.clearAlias()]

Add-ons can also define aliases in a file
slash_commands.json
With the following format

{
  "slashCommands": [
    {
      "name": "testSlashCommand",
      "description": "A Test Slash Command",
      "command": "This is a test"
    }, 
    {
      "name": "testSlashCommand1",
      "description": "A Test Slash Command 1",
      "command": "This is a test 1"
    } 

  ]
}

This will take care of registering the aliases for you so that you do not need to create any onCampaignLoad macro, it will also separate the commands for your add on in the /alias command listing into their own heading like

Aliases set via macros and add ons have a different "lifetime" to those set using the /alias command.
When set by macro, the aliases are cleared when a new campaign is created, or a campaign is loaded. This is so campaign set aliases will not pollute each other. They are not saved as part of the campaign, so they must be recreated each time if not defined the slash_commands.json file in an add-on.

To maintain functional compatibility, aliases created with /alias command will persist across campaign load/creation and /savealias will not save alises created with slash.setAlias() or add-ons.

Possible Drawbacks

See the above discussion about differences between aliases set with new macro functions and /alias

Documentation Notes

See above

Release Notes

• Add new macro functions for dealing with slash commands
• Add ability for add-ons to define slash commands

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This change is 

[thelsing]

I didn't find any references to MtScript2Lexer. Is it already used or was it added accidentally?

[cwisniew]

I didn't find any references to MtScript2Lexer. Is it already used or was it added accidentally?

yeah it was something I was working on in another branch when I switched back to implement a few extra things people on discord wanted (those are IDE generated files) no idea why it wasn't cleaned up properly and made it into this PR will make sure its not there when I complete the changes requested and push final PR