Fix shortcuts firing while user inputs text

[carolhmj]

Forum issue: https://forum.babylonjs.com/t/gui-editor-shortcuts-bug-on-inputtext/32884

[azure-pipelines]

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[azure-pipelines]

Snapshot stored with reference name:
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Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12855/merge/index.html

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