[xp] refactor keys class

Coverage report for experimental massa-web3

St.^{:grey_question:}	Category	Percentage	Covered / Total
🔴	Statements	58.75% (+0.15% 🔼)	611/1040
🔴	Branches	36.91% (-0.32% 🔻)	86/233
🔴	Functions	57.87% (+0.65% 🔼)	114/197
🔴	Lines	58.86% (+0.15% 🔼)	611/1038

Show files with reduced coverage 🔻

St.^{:grey_question:}

| File | Statements | Branches | Functions | Lines | | :-: | :- | :- | :- | :- | :- | | 🟢 |

`...` / keys.ts

97.5% (-2.5% 🔻)

77.78% (-22.22% 🔻)

| 100% |

97.5% (-2.5% 🔻)

| | 🟢 |

`...` / account.ts

87.04% (-0.89% 🔻)

| 46.15% | 100% |

87.04% (-0.89% 🔻)

| | 🟢 |

`...` / internal.ts

91.67% (-8.33% 🔻)

| 100% | 100% |

91.67% (-8.33% 🔻)

55 tests passing in 10 suites.

Report generated by 🧪jest coverage report action from 58bcca00534f65a96682a07ac45e9f2644202eaa