[mercury] Refactor package distribution to improve code splitting and remove code duplication

[ncamera]

Changes we propose in this PR:

• Refactor package distribution to improve code splitting.

  • Some files have been splitted into multiple files to reduce the bundle size when individual library functions. In other words, each feature can now be imported specifically by its path:

    import { getBundles } from "@genexus/mercury/dist/bundles";
    import { getImagePathCallbackDefinitions } from "@genexus/mercury/dist/assets-manager";

    There are still some changes to simplify import paths.

  • This also fixes a side effect where the MERCURY_ASSETS definition could be duplicated in some projects using multiple library functions.

• Added ESBuild to reduce the size of the JS files.

Breaking changes

• Mercury assets must now be explicitly set, using the following:

  import { registerMercury } from "@genexus/mercury/dist/register-mercury";
  registerMercury();

  Previously, registration was done as a side effect when importing some library functionality.