Experimental user scripts support (#857)

* version 0.5

* fix whitespace errors and rebase with 87.0.4280.106

* fix bug [FATAL:utf_string_conversions.cc(338)] Check failed: IsStringASCII(utf16). Tampermonkey • Userscript Sources

* add details for unmatch header, bug DOCUMENT_START not work, add a flag for logging

* deny network access to injected scripts

* removed log + fix ui + upstream update (@9f2aac4)

* update patch for v88

* force char as unsigned in invalidChar

* adapt to v89, add view script source, replace checkbox in preferences, removed extension work, add support to non-standard @url declaration, use saf directly

* updates for v90

* update for v91

* remove flag and keep only toggle
tell that the script has failed with errors
remove copy to temporary file
remove approach with XML overlays so that there are no exceptions thrown while inflating

* change install message + add homepage support + make url clickable

* adaptation for v92

* v93 ready

* add prompt also after selecting file by ui, remove prefs addon patch, add commit message

* add README.md