debug/elf: add (*File).DynValue #56892
Description
DynString currently offers functionality to retrieve only string-valued .dynamic entries (e.g. entries described here as "string table offset of..."). However, many of them do not correspond to entries in the string table, and it would be useful to be able to extract those values too (e.g. to determine whether a binary is a PIE via the DF_1_PIE flag).