Add ModelNode.ToPrettyPrint() function

[SubPointSupport]

ModelNode has a good override of .ToString() method to provide a first look on the actual model node and definition.

It is desired to have .ToPrettyPrint() function which would print out the actual model tree in indent-based string. Extremely useful for the debugging, tracing purposes especially for the M2 Reverse library.

[SubPointSupport]

Implemented as DefaultPrettyPrintService with the following API:

Console.Write(model.ToPrettyPrint());
Console.Write(SPMeta2Model.ToPrettyPrint(model));

The output looks as following:

[WebDefinition] - Title:[] Description:[] Convert(p.LCID):[1033] Convert(p.UseUniquePermission):[False] Url:[/] WebTemplate:[] CustomWebTemplate:[]
    [WebDefinition] - Title:[7f4bf855bbb047459316a4463787b44c] Description:[9535d3d356874538a9186ab4eef18cfb] Convert(p.LCID):[1033] Convert(p.UseUniquePermission):[False] Url:[0720bb4b62714193] WebTemplate:[STS#0] CustomWebTemplate:[]
        [DeleteQuickLaunchNavigationNodesDefinition] - SPMeta2.Definitions.DeleteQuickLaunchNavigationNodesDefinition 
        [FeatureDefinition] - Title:[SharePoint Server Publishing] Convert(p.Id):[94c94ca6-b32f-4da9-a9e3-1f3d343d7ecb] Convert(p.Scope):[Web] Convert(p.Enable):[True] Convert(p.ForceActivate):[False]
        [ListDefinition] - Title: [ee67643598e540568d4c4a124da30a5e] Url: [b48ba77a11114703] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [a18e63b4634e4a67a78fcabda1608932] Url: [542b5eb5394849d1] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [7c2c8cd1372d4be288b41a2691e3c9c1] Url: [37236ac1793e4cea] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [e04f8463f9a84b218d5ee29d0ddfa8ce] Url: [62160a7eff3f49e5] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [1e077b79050443b18deefeba6eb48d69] Url: [1013bbc2c410413f] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [1c28254112b04efda2fa39264ef2298b] Url: [604030ce70a1405f] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [2e550c96a0544f219bbd2795bb5ee479] Url: [571cdafd778b4a63] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [d7fec91d1e4249169e01f286d690db37] Url: [89cd379d577e4485] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [8ae1d0b91c6242b1bac3648e80798fb8] Url: [f6966904368e4735] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]
        [ListDefinition] - Title: [411d2b8bd5e04d5e91729d13378ef00f] Url: [d461066713214309] ContentTypesEnabled:[True] TemplateType:[101] TemplateName:[]