Fix Code Quality Findings

[Morgy93]

This pull request updates the CHANGELOG.md to provide more informative release links and refines the test assertions in ddev-utils.test.ts for clarity and best practices. The most important changes are grouped below:

Documentation improvements:

• Updated all version entries in CHANGELOG.md to include comparison links for easier navigation between releases. [1] [2] [3] [4] [5] [6]
• Enhanced the description of the release management feature in the changelog for better clarity.

Test improvements:

• Replaced direct assertion of stub call counts with sinon.assert.calledOnce for improved readability and consistency in ddev-utils.test.ts. [1] [2] [3]
• Improved assertion for undefined values by using assert.ok(result.errorType === undefined) instead of strict equality, and clarified conditional message checks in error handling tests. [1] [2]