[Feature] Ability to interact with ProgressBar elements

[jamesmcroft]

Describe the feature and how it will be used

Introduce the ability to interact with the Uno Platform ProgressBar element.

There should be properties for retrieving the percentage value and whether it's in an indeterminate state.

Platforms

• iOS
• Android
• WebAssembly

[naajiha]

@jamesmcroft would love to take on this issue if possible! Thanks in advance