implementation of the function ft_read_file

Create a function to check whether or not a fd exists in a static list.

If the fd does not exist in the static chained list stash :

• create a new struct Stash_list
• store the fd value in the fd member
• initalize member buffer with NULL
• Update static linked list stash
• return the created fd list

If the fd exists in the static chained list :

• return fd list

implementation of the function ft_get_line