[pkg/ottl] Add a new converter that checks for sub-string

[khushijain21]

Component(s)

pkg/ottl

Is your feature request related to a problem? Please describe.

We have a use case where we would like to edit the attributes if the log body contains a sub-string.

Describe the solution you'd like

A new convetrer named ContainsSubString(log.body. "warn")

Describe alternatives you've considered

No response

Additional context

No response

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[github-actions]

Pinging code owners:

• pkg/ottl: @TylerHelmuth @evan-bradley @edmocosta

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[VihasMakwana]

Sounds good. Let's wait for codeowners' thoughts.