[Feature]: build an initial version of the playground for exploring how to use nsv

[purpleclay]

Describe your feature

Build a playground TUI that can be launched from the nsv CLI. The initial version of the playground should allow exploration of nsv features and how they impact the construction of a tag. For this initial version, load a pseudo repository into memory that the user can edit to trigger different behaviours within nsv.

Any additional information?

No response

Code of Conduct

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