feat(chart/opensearch): add ability for serviceMonitor basicauth

[eyenx]

Description

Right now there is non possibility to set a basicAuth configuration for the serviceMonitor. This PR adds it

Check List

• [x] Commits are signed per the DCO using --signoff

For any changes to files within Helm chart directories:

• [x] Helm chart version bumped
• [x] Helm chart CHANGELOG.md updated to reflect change

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