[FL-3884] Proper integer parsing (#3839)

* feat: strint_to_uint32 and tests
* fix: permit explicit bases and prefixes
* feat: strint_to_{int32,uint16,int16}
* feat: strint_to_u?int64
* refactor: replace strtol, strtoul, sscanf with strint_to_*
* fix: api symbols
* docs: document parameter `end` of strint_to_uint_32
* style: apply changes requested by hedger
* refactor: fix pvs-studio diagnostic
* style: apply changes requested by CookiePLMonster
* fix: unused var
* fix: pointer type
* refactor: convert atoi to strint_to_*
* fix: strint_to_uint8 doesn't actually exist ._ .
* fix: memory leak
* style: address review comments
* Toolbox: couple small comments in the code and doxygen comment update. SubGhz, Loader: fix strint usage.
* Loader: fix incorrect cast

Co-authored-by: あく <alleteam@gmail.com>

targets/f7/api_symbols.csv

@@ -242,6 +242,7 @@ Header,+,lib/toolbox/stream/buffered_file_stream.h,,
 Header,+,lib/toolbox/stream/file_stream.h,,
 Header,+,lib/toolbox/stream/stream.h,,
 Header,+,lib/toolbox/stream/string_stream.h,,
+Header,+,lib/toolbox/strint.h,,
 Header,+,lib/toolbox/tar/tar_archive.h,,
 Header,+,lib/toolbox/value_index.h,,
 Header,+,lib/toolbox/varint.h,,
@@ -3266,6 +3267,12 @@ Function,-,strerror,char*,int
 Function,-,strerror_l,char*,"int, locale_t"
 Function,-,strerror_r,char*,"int, char*, size_t"
 Function,+,string_stream_alloc,Stream*,
+Function,+,strint_to_int16,StrintParseError,"const char*, char**, int16_t*, uint8_t"
+Function,+,strint_to_int32,StrintParseError,"const char*, char**, int32_t*, uint8_t"
+Function,+,strint_to_int64,StrintParseError,"const char*, char**, int64_t*, uint8_t"
+Function,+,strint_to_uint16,StrintParseError,"const char*, char**, uint16_t*, uint8_t"
+Function,+,strint_to_uint32,StrintParseError,"const char*, char**, uint32_t*, uint8_t"
+Function,+,strint_to_uint64,StrintParseError,"const char*, char**, uint64_t*, uint8_t"
 Function,-,strlcat,size_t,"char*, const char*, size_t"
 Function,+,strlcpy,size_t,"char*, const char*, size_t"
 Function,+,strlen,size_t,const char*