Phone number input validation

[nus-se-script]

Users might want to be able to add symbols like + or - in a phone number, especially if it's long (for example, +65 1-800-1111-1111). They might even want to add clarifying notes such as (HP) +65-9123-4567 (Office) +65-6123-4567. It might be better to warn rather than block such inputs!

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_{[original: nus-cs2103-AY2324S1/pe-interim#2098] [original labels: severity.Low type.FeatureFlaw]}

[laurenlim2112]

Team's Response

Our target users would only be adding secondary school students from Singapore into the application. These students are unlikely to have an office phone number that is worthy of keeping track, or a particularly long phone number.

Duplicate status (if any):

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