Added access to the stride of image params
Added access to the stride of image params

Useful for making static promises about the stride


Former-commit-id: c74b07a115436f9ae624d474dad9cb0d9629b7ea
Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,darkbuck/Halide,Trass3r/Halide,darkbuck/Halide,Trass3r/Halide,Trass3r/Halide,Trass3r/Halide,darkbuck/Halide