Fix separator inside print
Fix #2677 and #2668.
I think global_sep_space isn't needed because we set the sep to " " as the default when it's not specified.
I couldn't figure out why that if condition of two consecutive non characters was in place and also why sep_no_space was used.
When the if condition of two consecutive non characters was false, the empty separator was being pushed.
In LFortran ASR, Print node was refactored to only contain StringFormat or a single StringConstant.
Also for StringFormat, only FormatFortran is implemented as of now.
https://github.com/lfortran/lfortran/issues/2543
https://github.com/lfortran/lfortran/pull/4696
I think this should be done after libasr in LPython is synced to LFortran.