refactor(context): refactor context handling and improve test robustness (#4066)

Use assert.InDelta for float comparison with tolerance in TestContextGetFloat32
Remove unnecessary blank line in TestContextInitQueryCache
Replace anonymous struct with named contextKey type in TestContextWithFallbackValueFromRequestContext
Update context key handling in TestContextWithFallbackValueFromRequestContext to use contextKey type

context.go

@@ -951,7 +951,7 @@ func (c *Context) ShouldBindBodyWithTOML(obj any) error {
 	return c.ShouldBindBodyWith(obj, binding.TOML)
 }
 
-// ShouldBindBodyWithJSON is a shortcut for c.ShouldBindBodyWith(obj, binding.JSON).
+// ShouldBindBodyWithPlain is a shortcut for c.ShouldBindBodyWith(obj, binding.Plain).
 func (c *Context) ShouldBindBodyWithPlain(obj any) error {
 	return c.ShouldBindBodyWith(obj, binding.Plain)
 }