[otel-collector] - rename otelcol to otel-collector

[puckpuck]

Changes

Renames otelcol to otel-collector

This is part of getting all services renamed based on the overall #1788 effort for all components in the demo.

Merge Requirements

For new features contributions, please make sure you have completed the following
essential items:

• CHANGELOG.md updated to document new feature additions
• Appropriate documentation updates in the docs
• Appropriate Helm chart updates in the helm-charts

Maintainers will not merge until the above have been completed. If you're unsure
which docs need to be changed ping the
@open-telemetry/demo-approvers.

[julianocosta89]

Had to add/move the otelcol-config-extras to the new folder.

Tested and now it works 🚀

[rogercoll]

Just a reminder that the OpenTelemetry collector binary name is structred as otelcol-<distribution> in https://github.com/open-telemetry/opentelemetry-collector-releases/tree/main/distributions.

But for the OpenTelemetry demo, your name suggestion gives more context to the users.