Implement method to check if string is present in Trie.

[sak-codes]

References to other Issues or PRs or Relevant literature

Brief description of what is fixed or changed

Other comments

[czgdp1807]

Seems like code quality tests are failing.

[codecov[bot]]

Codecov Report

Merging #517 (6018c90) into main (aafe3c2) will increase coverage by 0.002%. The diff coverage is 100.000%.

:exclamation: Current head 6018c90 differs from pull request most recent head cffeef0. Consider uploading reports for the commit cffeef0 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #517 +/- ## ============================================= + Coverage 98.539% 98.541% +0.002% ============================================= Files 32 32 Lines 4039 4046 +7 ============================================= + Hits 3980 3987 +7 Misses 59 59 ``` | [Impacted Files](https://codecov.io/gh/codezonediitj/pydatastructs/pull/517?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=codezonediitj) | Coverage Δ | | |---|---|---| | [pydatastructs/strings/trie.py](https://codecov.io/gh/codezonediitj/pydatastructs/pull/517?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=codezonediitj#diff-cHlkYXRhc3RydWN0cy9zdHJpbmdzL3RyaWUucHk=) | `100.000% <100.000%> (ø)` | | [](https://codecov.io/gh/codezonediitj/pydatastructs/pull/517?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=codezonediitj)