fix(Dev-Server): Edit ChartPropsConfig reexport to be a type object

[rtexelm]

SUMMARY

This should solve the warning that ChartPropsConfig does not exist in superset-ui-core/src/chart/models/ChartProps
See here and here

Example of warning fixed:

WARNING in ./packages/superset-ui-core/src/chart/index.ts 24:0-28
export 'ChartPropsConfig' (reexported as 'ChartPropsConfig') was not found in './models/ChartProps' (possible exports: default)

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API