Improve contributor workflow

[jakedetels]

The main purpose of this PR is to improve the workflow for developers contributing to ModelFusion. Changes include:

• support TypeScript declaration maps during local development, allowing easier navigate to source .ts files in IDEs.
• updated instructions in each examples README.md to include a required build step that was missing.
• updated package.json dev/dependencies to point to "workspace:*" for all workspaces within the monorepo (see https://pnpm.io/workspaces#publishing-workspace-packages for how those values get updated during publishing)
• added dev command to package.json scripts to facilitate local development (building in watch mode)
• updated CONTRIBUTING.md with additional details
• updated certain example files to allow them to be executed either from the monorepo root directory or from each example's root package folder.
• updated GoogleCustomSearchTool.ts to handle for cases where API responds with an error (such as a 403)

[lgrammel]

Sweet, now I understand why you moved the dts config.

Will land once conflicts are resolved!