Add validation for leading zeros in visual version

[Iuliia Kulagina (kullJul)]

Description:

• Adds a pre-build check that flags visual versions containing leading zeros, which are rejected by the Power BI marketplace package acceptance check.

Changes

• New feature VisualVersionLeadingZeros (src/features/VisualVersionLeadingZeros.ts) - a [PreBuild], [Warning]-severity, certification-relevant check that fails when any version part has a leading zero (e.g. 1.16.0345.1), with guidance to use 1.16.345.1 and update [pbiviz.json].
• src/Visual.ts - adds hasVisualVersionLeadingZeros().
• src/features/index.ts - registers the new feature.
• [spec/unit/FeatureManagerSpec.js] - unit tests covering versions with/without leading zeros.

Notes

• Warning-level only; does not block builds, surfaces the issue early before marketplace submission.
• Single commit: Add check for leading zeros in version.