fix(F-D10): ELF-loader get_string_in_section method

[sonicfromnewyoke]

Problem

Mithril's ELF loader getString() function doesn't properly handle string parsing from ELF string tables when the requested maximum length would exceed section bounds.

Summary of Changes

• migrate fn get_string_in_section logic
• move sbpf-related errors into sbpf package
• replace some unneeded formatings like fmt.Sprintf("ja") with strings directly, like "ja"

closes #118

cc @smcio