Hakawai: VONCALL-1788, Crash on Mentions
Hakawai: VONCALL-1788, Crash on Mentions

- Forcefully we are able to reproduce this crash by passing nil value in [NSString hasPrefix:] for non english language.
  Currently for case insensitive search, first we convert both strings to lowercase & then compare,
  which is wrong as it may give incorrect result (It may cause the crash but we were unable to repro this case).
- So we have changed this logic to use [NSString rangeOfString: options:] instead.

linkedin/Hakawai,linkedin/Hakawai,linkedin/Hakawai