Add number separators (commas) for block numbers

[kylanhurt]

Describe the bug
Without number / thousands separators it becomes more difficult to read block numbers.

To Reproduce
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Expected behavior
A clear and concise description of what you expected to happen.

Screenshots

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.

[matthewdarwin]

Some languages use spaces, some use commas. The choice of 1000s separator character should depend on browser config, not hard-coded value.

[kylanhurt]

@matthewdarwin Agreed. Current PR uses toLocaleString() which leaves it up to the browser.