fix(rust/signed-doc): Fix ExtraFields::from_protected_header error return

[Mr-Leshiy]

Description

Updated ExtraFields::from_protected_header to return Option<Self> instead of unused Result.
Fixed issue with returning an invalid result when error_report argument passed with already predefined some error reports inside it.

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 273/273}$ | ${\color{red}Fail: 0/273}$ |

[bkioshn]

LGTM

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 275/275}$ | ${\color{red}Fail: 0/275}$ |

[github-actions]

✅ Test Report | ${\color{lightgreen}Pass: 275/275}$ | ${\color{red}Fail: 0/275}$ |