feat(text): add client sample code

[chuang8511]

Because

• we want developers to be able to see the result without login into Instill Cloud

This commit

• expose text component function
• add the example section for golang client

[linear]

INS-5847 [Feat.] Replace langchaingo textsplitter package for open-source users

[jvallesm]

Ported to instill-ai/pipeline-backend#682