Number parsing

[estebanmino]

Custom implementation for renderFromTokenMinimalUnit, no less than 0.0001

opts with

• decimals to show
• significant decimals

Currencies are with 5 decimals by default instead of showing the specific currency decimal numbers
Don't show decimals if no decimals

[omnat]

@wachunei related to the issues you found. let's make improve those unit tests so we catch similar number format errors everywhere in the app

[omnat]

Sync with Mark and Rachel on this: on which library to use for rendering numbers and internationalization standard we'd use cross-product

[omnat]

Notes from meeting:

Let's find a standardized way of dealing with this

1. Number processing:
   - Turn all number inputs into a string before passing them through Big Number
   - Use Ethers BigNumber library consistently for manipulating the strings to number
2. Rendering:
   - Internationalization library for FIAT (between different currencies): some conversation here https://app.zenhub.com/workspaces/metamask-mobile-5f984938ddc0e4001d4b79cb/issues/metamask/metamask-mobile/2137
   - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat
   - Rendering crypto values:
   - Extension shows accurate values in decimal (no rounding), only exception is trailing zeroes
   - Design guidelines so far on this: https://www.figma.com/file/aWgwMrzdAuv9VuPdtst64uuw/MetaMask-Design-System?node-id=1628%3A1871

[omnat]

Next steps: Write a proposal on how to parse numbers reliably and consistently.
cc @andrepimenta @wachunei

[mobularay]

With @andrepimenta moving to the Core team, this ticket should wait until the Core team has an agreed way of implementing number parsing.

Needs to split work into:

1. (Technical) Research / Proposal
2. UI/UX Design work
3. Implementation work

[legobeat]

Related: #12043