Fix transaction confirmation

[jstarry]

Problem

The confirm transaction section is not working correctly. After pasting a valid transaction signature, the input validation shows an error.

Proposed Solution

• Check if the signature input validation is incorrectly using public key input validation (that's my guess)
• Add an error message to help users know why the signature was not considered valid

[jstarry]

[jstarry]

Test signature: TGMxacDao8m6ficsFrtmR3UademYWZperUN9t34EyUhn3jyUHs4mT6Vmk1yFrePPHum7YT2AirZfR1JtiFsNtuq