Bug fix: Add @rollup/plugin-node-resolve to rollup configuration

[juliangilbey]

Summary

Proposed changes

When building the package, rollup warns:

src/cli/index.ts → dist/cli.js...
(!) Unresolved dependencies
https://rollupjs.org/troubleshooting/#warning-treating-module-as-external-dependency
svgicons2svgfont/src/filesorter (imported by "src/standalone/glyphsData.ts")
svgicons2svgfont/src/metadata (imported by "src/standalone/glyphsData.ts")
created dist/cli.js in 5.8s

src/index.ts → dist...
(!) Unresolved dependencies
https://rollupjs.org/troubleshooting/#warning-treating-module-as-external-dependency
svgicons2svgfont/src/filesorter (imported by "src/standalone/glyphsData.ts")
svgicons2svgfont/src/metadata (imported by "src/standalone/glyphsData.ts")

This PR follows the advice in the referred-to website, and adds the @rollup/plugin-node-resolve plugin to the rollup configuration.

Dependencies added/removed (if applicable)

• Add: @rollup/plugin-node-resolve;

I have added this to package.json but not modified package-lock.json.

The package builds (on Debian) with this patch without the rollup warnings.

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Checklist

• I have added corresponding labels to this PR (like bug, enhancement...);
• My commits follow the Conventional Commits 1.0 Guidelines;
• My code follows the style guidelines of this project;
• I have performed a self-review of my own code;
• I have mapped technical debts found on my changes;
• I have made changes to the documentation (if applicable);
• My changes generate no new warnings or errors;