[redis]: Use Readline to read large value

[marcaudefroy]

By default, Scanner uses a buffer with 64K capacity. So when we try to set a huge redis value (>64K), executor failed to read file. The fix consists to use Readline method. (source https://devmarkpro.com/working-big-files-golang).

Before :

 ./venom run ./../../tests/redis.yml
 • Redis testsuite (./../../tests/redis.yml)
 	• Commands_Test_Case SUCCESS
 	• File_Test_Case SUCCESS
 	• Long_Value_File_Test_Case FAILURE
Testcase "Long_Value_File_Test_Case", step #1: Failed to load file: bufio.Scanner: token too long (./../../tests/redis.yml:50)
 	• Commands_Nested_Array_Response_Test_Case SUCCESS
	  [info] streamEntry1ID: OK (./../../tests/redis.yml:70) (./../../tests/redis.yml:70)
	  [info] streamEntry2ID: 1639752707532-1 (./../../tests/redis.yml:72) (./../../tests/redis.yml:72)

After :

   ./venom  run -v ./../../tests/redis.yml
	  [trac] writing venom.log
 • Redis testsuite (./../../tests/redis.yml)
 	• Commands_Test_Case SUCCESS
 	• File_Test_Case SUCCESS
 	• Long_Value_File_Test_Case SUCCESS
 	• Commands_Nested_Array_Response_Test_Case SUCCESS
	  [info] streamEntry1ID: OK (./../../tests/redis.yml:70) (./../../tests/redis.yml:70)
	  [info] streamEntry2ID: 1639753471610-1 (./../../tests/redis.yml:72) (./../../tests/redis.yml:72)