Escape sequences should be treated as single characters.

[faze-geek]

Realized this while working on #1589
Escape sequences are treated as 2 characters of a string in Lpython unlike in python. Although it is a small block and the if condition can be modified accordingly for the pull request, it should be corrected.

A minimal example is this -

def f():
    print(len("\t"))        # Single character for tab space
    print(len("\n"))        # Single character for new line
    print(len("\0"))        # Single character for null
    
f()

(lp) C:\Users\kunni\lpython>python try.py
1
1
1

(lp) C:\Users\kunni\lpython>src\bin\lpython try.py
2
2
2

[harshitmathur2000]

@certik I want to work on this issue. I am new, so, can you guide which file to look for to handle this?