Remove FluidDataStoreContext.request

[ChumpChief]

This is internal and has been deprecated for a long time. Seems safe to remove.

Also removes some use of mixinRequestHandler from prosemirror/codemirror, since they don't actually issue requests in those demos.

[Copilot]

Copilot reviewed 3 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (3)

• examples/data-objects/codemirror/package.json: Language not supported
• examples/data-objects/prosemirror/package.json: Language not supported
• pnpm-lock.yaml: Language not supported

Comments suppressed due to low confidence (3)

packages/runtime/container-runtime/src/dataStoreContext.ts:796

• Ensure that tests are updated to reflect the removal of FluidDataStoreContext.request so that downstream behavior is not inadvertently affected.

public async request(request: IRequest): Promise<IResponse> {

examples/data-objects/prosemirror/src/prosemirror.tsx:110

• Confirm that the removal of the request method and mixinRequestHandler does not affect demo functionality, and verify that tests cover the updated runtime instantiation.

public async request(req: IRequest): Promise<IResponse> {

examples/data-objects/codemirror/src/codeMirror.ts:83

• Ensure that tests verify the demos function correctly after removing the request method and mixinRequestHandler usage.

public async request(req: IRequest): Promise<IResponse> {