Checks if any row has descendants not expanded; fixes #701

[jaimeatstariongroup]

Prerequisites

• [x] I have written a descriptive pull-request title
• [x] I have verified that there are no overlapping pull-requests open
• [x] I have verified that I am following the COMET-IME code style guidelines
• [x] I have provided test coverage for my change (where applicable)

Description

The IHaveContainedRows interface contains a new method. The implementation of that interface checks if the row has any descendants not expanded.

[sonarcloud[bot]]

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0 Bugs
0 Vulnerabilities
0 Security Hotspots
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78.3% Coverage
0.0% Duplication