fix: correctly show rows after showing hidden column and clearing grid filter

[hdamr]

Description

When grid is used with an in-memory data provider with more than 50 items, after applying a filter and hiding a column and respectively making the column visible and filter cleared (in this particular order), grid breaks and it won't show items correctly unless page is refreshed.

The current fix simply resolves by checking for cell parent not being null in __setColumnTemplateOrRenderer method, and by doing so the issue is resolved. I have added a relevant test case which tests this particular behaviour.

This PR is rebased on top of master (which includes all changes made into running tests)

Fixes vaadin/flow-components#2330

Type of change

• Bugfix
• Feature

Checklist

• I have read the contribution guide: https://vaadin.com/docs/latest/guide/contributing/overview/
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.

Additional for Feature type of change

• Enhancement / new feature was discussed in a corresponding GitHub issue and Acceptance Criteria were created.