All package.json files in Tuleap should have "type"="module" to switch to ES modules by default. Since request #27548 is finished and Jest is gone, there is no obvious reason binding us to CommonJS anymore (excluding surprises, of course…).

Switching to ESM should simplify our build steps : we can drop UMD builds for libraries, we can drop "require" rules for "imports" blocks in package.json.

As a side-quest, we can also remove types from the root package.json. TypeScript should now use moduleResolution: bundler and follow rules from imports, so it should not be needed anymore.