Clear previous fake function behaviors before setting new ones

[sung-gon-kim]

When setting the behavior of a fake function, there are cases where previously registered behaviors need to be removed according to priority. Especially with test fixtures, these can sometimes be missed, which may lead to unintended behavior.

To prevent this, the following macros have been updated to clear any existing fake behaviors before applying new ones:

• SET_RETURN_SEQ
• SET_CUSTOM_FAKE_SEQ

Additionally, new macros have been introduced for setting return_val and custom_fake variables. These new macros also clear any previously registered behaviors before setting the new ones:

• SET_RETURN_VAL
• SET_CUSTOM_FAKE

These changes ensure that fake functions behaviors are always applied cleanly, avoiding conflicts or overlaps from prior configurations.

• Your code builds clean without any errors or warnings
• You are not breaking consistency
• You have added unit tests
• All tests and other checks pass