typed parameters

[earloc]

Enables usage of type-annotations in parameter-tokens.

e.g. string in Hello {name:string}

initial support is done for the following types:

alias	type	example usage (alias)	example usage (type)
i	int	{count:i}	{count:int}
s	string	{name:s}	{name:string}
dt	DateTime	{date:dt}	{date:DateTime}
dto	DateTimeOffset	{date:dto}	{date:DateTimeOffset}
d	DateOnly	{date:d}	{date:DateOnly}
t	TimeOnly	{time:t}	{time:TimeOnly}

one cann still omit the type-annotation, which will fall back to using object. However, if a type-annotation cannot be matched, the source-generator falls back to object, too, but emits a warning, additionaly.
See docs/reference/TR0004_UnrecognizedParameterType.md for further details.

Additionaly, this PR simplifies emitted diagnostics-codes.

closes #6