Make SetResource return status, and call it synchronously in Batch[Log|Span]Processor

[lalitb]

Changes

As discussed here

Make SetResource return status, and call it blockng in Batch[Log|Span]Processor. This makes the setting of resources during initialization deterministic.

Earlier

LogExporter::set_resource(&mut self, resource: &opentelemetry_sdk::Resource);
LogProcessor::set_resource(&self, _resource: &Resource);

SpanExporter::set_resource(&mut self, resource: &opentelemetry_sdk::Resource);
SpanProcessor::set_resource(&self, _resource: &Resource);

Now:

LogExporter::set_resource(&mut self, resource: &opentelemetry_sdk::Resource) -> LogResult<()>;
LogProcessor::set_resource(&self, _resource: &Resource) -> LogResult<()>;

SpanExporter::set_resource(&mut self, resource: &opentelemetry_sdk::Resource) -> -> ExportResult
SpanProcessor::set_resource(&self, _resource: &Resource) -> -> ExportResult

Please provide a brief description of the changes here.

Merge requirement checklist

• [x] CONTRIBUTING guidelines followed
• [x] Unit tests added/updated (if applicable)
• [ ] Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• [x] Changes in public API reviewed (if applicable)