Add autostart feature with per-IDB preference

[hzqst]

Auto-patch PLT section when IDA opens an ELF64 database, with a configurable toggle under Edit -> Plugins -> PLT Patcher Configuration. Preference is stored per-IDB via netnode and defaults to enabled.

Tested and working fine on my end:

[hzqst]

Changes:

• Moved the autostart setting from per-IDB netnode storage to a user-global JSON config file (plt_patcher.json).

• Added compatibility logic to resolve the IDA user config directory via idaapi, ida_diskio, IDAUSR, or ~/.idapro.

• Changed the configuration prompt to describe a user-wide setting instead of a database-specific one.
  Made config read/write failures fall back safely: default to enabled, and keep session changes even if persistence fails.

• Added ida_auto support to wait for IDA auto-analysis before running PLT patching.

• Introduced _wait_for_auto_analysis(), which skips waiting if analysis is already finished and otherwise blocks with ida_auto.auto_wait().

• Updated run() so both autostart and manual execution go through the same “wait first, then patch” path.
  This prevents patch_plt() from running too early and avoids errors like bad call add_dref.

Test result: