fix(eslint-plugin): separate legacy and modern dts files (#8972)

* chore(build): restructure eslint-plugin-query build configuration

Aligned the build system with other packages by replacing the custom tsup config with standard modern/legacy build outputs. Moved output files from 'dist' to 'build' directory structure. Removed the patch-missing-export-equals.js script in favor of directly exporting the plugin. Added tsconfig.prod.json for production builds.

* chore(example): eslint classic

* ci: apply automated fixes

* fix: unique name for examples

* remove unused import

* chore: add eslint test script to react examples and update eslint test command

Add `test:eslint` script to react example package.json files to enable linting checks. Update the main `test:eslint` command to remove the exclusion of examples, ensuring linting is applied across the entire project.

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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: TkDodo <office@dorfmeister.cc>