[CHORE]: Remove Babel from `stackgl_modules` build process

[camdecoster]

Description

Remove Babel-related dependencies from the stackgl_modules build process.

Notes

• stackgl_modules is a pre-bundled vendor folder
• The stackgl_modules build process has used Babel to transpile the included dependencies to ES5 syntax
• plotly.js uses esbuild for bundling and that can handle the transpiling
• This was discovered in a recent dependabot PR (Bump the npm_and_yarn group across 2 directories with 2 updates #7846)

Scope

In stackgl_modules/webpack.config.js:

• Remove both babel-loader rules (the project-files rule is effectively a no-op without a babel config; the buffer/is-mobile rule is redundant with esbuild)
• Remove target: ['web', 'es5']

In stackgl_modules/package.json, drop the now-unused devDeps:

• @babel/core
• @babel/preset-env
• @babel/plugin-transform-modules-commonjs
• babel-loader

ify-loader (glslify) and raw-loader must stay — they handle the GLSL shader preprocessing that's the actual reason this pre-bundle exists.

Testing

• After removing the babel rules, run npm run bundle-stackgl
• Rebuild plotly.js and smoke-test 3D traces (scatter3d / mesh3d / surface) to confirm things still run/look the same