add function array seq(int m)

[9prady9]

ArrayFire 2.0 had this function where the call seq(int) would return an array with sequence [0, m-1]. Similar functionality needs to be added in 3.0

[shehzan10]

This functionality is available via iota. It is not required to be done using seq.

[9prady9]

@shehzan10 I think it still needs to go into af/compatible.h header if this was available in AF2.0. Also, it need not be member function of seq, so not related to seq class. It can call iota internally.

[9prady9]

@shehzan10 are you working on this ? if so, please assign it to yourself. If not, i can work on it.