fix: disallow transferring amounts <=0

[Dhaiwat10]

Summary

This PR introduces a new error to the transfer and transferToContract methods on the Account class which appears when a user tries to transfer an amount that's less than or equal to zero, as requested in the original issue.

Closes #1577

[github-actions]

Coverage Report:

Lines	Branches	Functions	Statements
79.47%(-0.01%)	70.21%(+0.01%)	78.04%(+0%)	79.56%(-0.01%)

Changed Files:

Ok	File (✨=New File)	Lines	Branches	Functions	Statements
🔴	packages/account/src/account.ts	78.29% (-0.91%)	55.73% (+1.35%)	85.71% (+0%)	78.29% (-0.91%)