fix(wallet): use hex-encoded blockCount param for eth_feeHistory

[onyb]

Resolves brave/brave-browser#23529

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

Checking known RPC endpoints to see if they support hex-encoded blockCount param to eth_feeHistory RPC method:

curl -s <url> -X POST -H "Content-Type: application/json" -d '{"id":1,"jsonrpc":"2.0","method":"eth_feeHistory","params":["0x28", "latest", [20,50,80]]}' | jq

RPC Name	RPC Endpoint	Supports hex blockCount
Ethereum (Brave)	https://mainnet-infura.brave.com	✅
Polygon (public)	https://polygon-rpc.com	✅
Polygon (Brave)	https://mainnet-polygon.brave.com	✅
Avalanche C-Chain (public)	https://api.avax.network/ext/bc/C/rpc	✅
Fantom (public)	https://rpc.ftm.tools	✅
Moonbeam (public)	https://rpc.ankr.com/moonbeam	✅

Optimism, Celo, BSC, and Aurora (NEAR) not included in the above table, since they do not support EIP-1559.

Please see linked issue for steps to reproduce for Moonbeam.

[srirambv]

Verification passed on

Brave	1.43.12 Chromium: 103.0.5060.114 (Official Build) nightly (64-bit)
Revision	a1c2360c5b02a6d4d6ab33796ad8a268a6128226-refs/branch-heads/5060@{#1124}
OS	Windows 11 Version 21H2 (Build 22000.778)

• Verified steps from Unable to complete Moonbeam transactions (Gas estimation fails) brave-browser#23529
• Verified able to successfully submit send transaction for Moonbeam
• Verified confirmation message is also shown for successful transactions

14088.mp4