show available device resources mode and than exit

[w0lek]

Proposed Behaviour

new command line argument

--show_resource_usage  {on, off}

runs vpr to print available device resources,
example of output :

FPGA sized to 3 x 3: 9 grid tiles (auto)

Resource usage for device layout auto...
	Architecture
		32	blocks of type: io
	Architecture
		1	blocks of type: clb
	Architecture
		0	blocks of type: dsp

and than exit normally.
Note: this report is already printed as regular vpr flow, Note: we want keep this format

Possible Solution

new command line argument and api entry to show available resource and exit