Add better hints for string type mismatch

[UdeshyaDhungana]

• Added better error messages for frequently occuring errors regarding string type mismatch

Before

After

---

Note

Improve RESP string type-mismatch diagnostics and add a ping-pong test scenario that reproduces bulk vs simple string errors.

• Assertions (RESP):
  • internal/resp_assertions/bulk_string_assertion.go: Add explicit error when a simple string matches expected bulk string.
  • internal/resp_assertions/simple_string_assertion.go: Add explicit error when a bulk string matches expected simple string.
  • internal/resp_assertions/bulk_string_present_in_array_assertion.go: Add diagnostic when matching simple string is found instead of bulk string in arrays.
• Tests:
  • internal/stages_test.go: Add ping_pong_string_type_mismatch case for stage rg2.
  • New scenario internal/test_helpers/scenarios/ping-pong/string_type_mismatch/ with fixture output to simulate returning $4\r\nPONG\r\n and validate improved messaging.

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