Update RoundAdmin page to configure metrics

[carlbarrdahl]

• Render ImpactConfig or CategoryConfig based on round.type
  • if round.type === impact ImpactConfig, if type === project CategoryConfig
• Create router endpoint metrics.search
  • Return available metrics (id, name, description) (Ask OSO for name and description for metrics)
• Create component for admin to select available metrics (react-select multi?)
• Store selected metrics in db round.metrics

Available metrics:

active_contract_count_90_days
address_count
address_count_90_days
days_since_first_transaction
display_name
event_source
gas_fees_sum
gas_fees_sum_6_months
high_activity_address_count_90_days
low_activity_address_count_90_days
medium_activity_address_count_90_days
multi_project_address_count_90_days
new_address_count_90_days
project_id
project_name
project_namespace
project_source
returning_address_count_90_days
transaction_count
transaction_count_6_months