feat: add UiInputAmount and decimals validation

[Sekhmet]

Summary

Closes: #583

This PR adds new UiInputAmount that can be used to input numeric amounts, but without drawbacks of using number input for it:

• Because it's no longer number it doesn't get converted to exponential form (for example in StakeToken modal output value would be displayed as 1e-7).
• Similarly when entering small value like 0.000000000000001 and triggering re-render, for example by going to contact picker and back it would be turned to exponential form.
• UiInputAmount value has consistent type (always string), where UiInputNumber could have either string (when input is empty) or number.

This PR also adds decimals validation so we can validate the form (SendToken and StakeToken).

How to test

1. Go there: http://localhost:8080/#/eth:0x6E60b6dCc2923267104Bb4a68F4766f627430664/treasury
2. Try creating SendToken execution, enter big values or small ones, trigger decimals error.
3. Try creating StakeToken execution, enter big values or small ones, trigger decimals error.
4. Nothing breaks.

Note: Currently if you enter error state (for example too many decimals) and open picker and back dirty flag gets cleared so it won't display the error on UI, but it's true for all inputs at the moment, we have issue for that: #573

Screenshots

Before

Screen.Recording.2024-08-06.at.16.30.14.mov

After

Screen.Recording.2024-08-06.at.16.30.50.mov

[bonustrack]

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