Remove type redundancy

[vlopes11]

Is your feature request related to a problem? Please describe.
The DAP types should be transparently represented as single rust types.

Currently, we have unnecessary redundancy with some types, such as Request::Continue, where we have arguments: ContinueArguments, when the variant Request::Continue should hold the arguments directly instead of declaring an intermediate type

dap-reactor/src/request.rs

Lines 32 to 34 in adc93e6

	Continue {
	arguments: ContinueArguments,
	},

Describe the solution you'd like
Simplify the types and remove the redundancy