Add cell-editing-custom-theme samples for hierarchical-grid and tree-grid

[Copilot]

• Remove all auto-generated README files that were accidentally added
• Keep only the two new sample folders

Summary

Removed 460 README files that were accidentally added by running gulp updateSamples. The PR now only contains the two new sample folders:

Files in PR:

• samples/grids/hierarchical-grid/cell-editing-custom-theme/ (10 files)
• samples/grids/tree-grid/cell-editing-custom-theme/ (10 files)

Total: 20 files for the two new samples only, with no existing files edited.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Create Cell Editing Styling Samples for hgrid and tgrid</issue_title>
<issue_description>create the same sample as per #927 but featuring hgrid and tgrid</issue_description>

<agent_instructions>Please create the sample as per the linked PR in the description. One sample where the main element is IgrHierarchicalGrid and another sample with IgrTreeGrid</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Fixes #928

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[tishko0]

@copilot Why have you edited so many files? Could you not access the PR in the information section for reference? I would expect that there are only 2 added folders with the new samples, and no existing files edited. Please update with the requested changes

[tishko0]

please add the changes from my last comment

[tishko0]

@copilot can you please remove the edits on the readme files. We do not want to edit anything existing

[Copilot]

@copilot can you please remove the edits on the readme files. We do not want to edit anything existing

Removed all 460 auto-generated README files. The PR now contains only the 20 files for the two new samples (hierarchical-grid and tree-grid cell-editing-custom-theme). Commit: ef2dda3