feat: add chainlink aggregator helper contract for subgraph service

[thorseldon]

• Chainlink maybe update the reserve internal aggregator but without any event
• Using this helper contract to manually trigger updating internal aggregator in subgraph service;
• Another solution is to track and process the ENS PublicResolver contracts AddrChanged event, Eg. aggregator.eth-usd.data.eth;

[codecov[bot]]

Codecov Report

Patch coverage: 56.41% and project coverage change: -0.57 :warning:

Comparison is base (a027918) 91.42% compared to head (9ecd232) 90.86%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #116 +/- ## ========================================== - Coverage 91.42% 90.86% -0.57% ========================================== Files 34 35 +1 Lines 2672 2694 +22 Branches 413 417 +4 ========================================== + Hits 2443 2448 +5 - Misses 229 246 +17 ``` | [Impacted Files](https://app.codecov.io/gh/BendDAO/bend-lending-protocol/pull/116?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BendDAO) | Coverage Δ | | |---|---|---| | [contracts/misc/ChainlinkAggregatorHelper.sol](https://app.codecov.io/gh/BendDAO/bend-lending-protocol/pull/116?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BendDAO#diff-Y29udHJhY3RzL21pc2MvQ2hhaW5saW5rQWdncmVnYXRvckhlbHBlci5zb2w=) | `0.00% <0.00%> (ø)` | | | [...cts/protocol/EmergencyTokenRecoveryUpgradeable.sol](https://app.codecov.io/gh/BendDAO/bend-lending-protocol/pull/116?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BendDAO#diff-Y29udHJhY3RzL3Byb3RvY29sL0VtZXJnZW5jeVRva2VuUmVjb3ZlcnlVcGdyYWRlYWJsZS5zb2w=) | `100.00% <100.00%> (ø)` | | | [contracts/protocol/LendPoolLoan.sol](https://app.codecov.io/gh/BendDAO/bend-lending-protocol/pull/116?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BendDAO#diff-Y29udHJhY3RzL3Byb3RvY29sL0xlbmRQb29sTG9hbi5zb2w=) | `96.66% <100.00%> (+0.08%)` | :arrow_up: | | [contracts/protocol/PunkGateway.sol](https://app.codecov.io/gh/BendDAO/bend-lending-protocol/pull/116?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BendDAO#diff-Y29udHJhY3RzL3Byb3RvY29sL1B1bmtHYXRld2F5LnNvbA==) | `96.31% <100.00%> (ø)` | | | [contracts/protocol/WrapperGateway.sol](https://app.codecov.io/gh/BendDAO/bend-lending-protocol/pull/116?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BendDAO#diff-Y29udHJhY3RzL3Byb3RvY29sL1dyYXBwZXJHYXRld2F5LnNvbA==) | `96.15% <100.00%> (ø)` | |

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