Add ETH override to tokenData API

[nathanhleung]

Right now, the ETH logo isn't showing up correctly on https://convex-ui.vercel.app/ (screenshot below) because the API doesn't return anything for 0x0000000000000000000000000000000000000000, which is the address we use in the dapp to denote regular Ether.

[vercel]

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🔍 Inspect: https://vercel.com/rari-capital/rari/2YWJGg7hGdwsvMD9uJxTrQr7Ak9d
✅ Preview: https://rari-git-nathanhleung-ethereum-override-rari-capital.vercel.app

[coveralls]

Pull Request Test Coverage Report for Build 1941949901

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 108 unchanged lines in 15 files lost coverage.
• Overall coverage decreased (-1.2%) to 9.843%

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Files with Coverage Reduction	New Missed Lines	%
src/hooks/rewards/useUnclaimedFuseRewards.ts	1	54.55%
src/hooks/useNoSlippageCurrencies.ts	2	50.0%
src/utils/fetchPoolAPY.ts	2	46.15%
src/hooks/usePoolBalance.ts	3	52.0%
src/rari-sdk/subpools/compound.js	3	13.33%
src/utils/bigUtils.ts	3	44.44%
src/rari-sdk/subpools/dydx.js	4	50.0%
src/utils/format.ts	4	9.09%
src/rari-sdk/governance.js	6	17.65%
src/rari-sdk/cache.js	7	47.37%

Totals
Change from base Build 1888586866:	-1.2%
Covered Lines:	962
Relevant Lines:	6993

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💛 - Coveralls

[github-actions]

Bundled size for the package is listed below:

build/static/js: 26.04 MB
build/static/css: 15.63 KB
build/static/media: 875.00 KB
build/static: 26.91 MB
build: 27.53 MB

[github-actions]

Bundled size for the package is listed below:

build/static/js: 26.04 MB
build/static/css: 15.63 KB
build/static/media: 875.00 KB
build/static: 26.91 MB
build: 27.53 MB