feat: Return default operation breakdown list from project options

[dashed]

Add sentry:breakdowns project options which will be consumed by Relay in getsentry/relay#934

These project options are hardcoded to a predefined list of span ops: "http", "db", "browser", "resource"

Reference: https://getsentry.atlassian.net/browse/VIS-617 and https://getsentry.atlassian.net/browse/VIS-698

The default config will be:

{
    "span_ops": {
        "type": "span_operations",
        "matches": ["http", "db", "browser", "resource"],
    }
}

TODO

• add feature flag from feat(flag): Add feature flags for segment explorer #24013