client-js: add JS helpers for interest bearing tokens' UIAmounts

[gitteri]

Similar to this PR in solana-program-library, this adds helper functions for interest bearing tokens for getting amountToUiAmount and uiAmountToAmount without needing to simulate a transaction.

1. amountToUiAmountForMintWithoutSimulation - converts a number/bigint amount for a given mint at the current time to a UiAmount
2. amountToUiAmountWithoutSimulation - converts a given number/bigint amount and detailed information about the mint's interest rates to a UiAmount
3. uiAmountToAmountForMintWithoutSimulation- converts a given ui amount string for a given mint at the current time to amount
4. uiAmountToAmountWithoutSimulation - converts a given ui amount string and detailed information about the mint's interest rates to amount

UiAmounts are provided with the token's decimals as its precision and truncated instead of rounded to avoid rounding issues.
Amounts are processed in the base unit of the token (if the token has 2 decimals 1.23 is represented as 123)

[joncinque]

Looks good to me overall! Mostly small things. @lorisleiva can you also take a quick look at the tests? I'm mostly interested in feedback on the test setup, and whether it aligns how we should write tests for these packages

[joncinque]

Same here, I would call this file amountToUiAmount.test.ts

[lorisleiva]

Thanks!

[lorisleiva]

Thanks for making the changes!

[joncinque]

Looks good to me! Can you run pnpm format:fix to fix the formatting issue? You might also need to rebase to pick up the recent changes to CI