feat: add search emoji by substring

[Lao-Ax]

Before the fix emoji could be found only by a subsctring from a string start.

For example, we have two emojis

1. foo
2. bar_foo

When you perform a search by keyword 'foo' only the first one will be found.

Now, both will be found.

Proposed changes

Issue(s)

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Types of changes

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves a current function)
• New feature (non-breaking change which adds functionality)
• Documentation update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if applicable)
• I have added necessary documentation (if applicable)
• Any dependent changes have been merged and published in downstream modules

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