Small cleanups to various data types. (#8086)

- Use `bst_bin_t` in batch param constructor.
- Use `StringView` to avoid `std::string` when appropriate.
- Avoid using `MetaInfo` in quantile constructor to limit the scope of parameter.

src/common/quantile.h

@@ -903,12 +903,11 @@ class HostSketchContainer : public SketchContainerImpl<WQuantileSketch<float, fl
   using WQSketch = WQuantileSketch<float, float>;
 
  public:
-  HostSketchContainer(int32_t max_bins, MetaInfo const &info, std::vector<size_t> columns_size,
-                      bool use_group, int32_t n_threads);
+  HostSketchContainer(int32_t max_bins, common::Span<FeatureType const> ft,
+                      std::vector<size_t> columns_size, bool use_group, int32_t n_threads);
 
   template <typename Batch>
-  void PushAdapterBatch(Batch const &batch, size_t base_rowid, MetaInfo const &info, size_t nnz,
-                        float missing);
+  void PushAdapterBatch(Batch const &batch, size_t base_rowid, MetaInfo const &info, float missing);
 };
 
 /**
@@ -1000,13 +999,12 @@ class SortedSketchContainer : public SketchContainerImpl<WXQuantileSketch<float,
   using Super = SketchContainerImpl<WXQuantileSketch<float, float>>;
 
  public:
-  explicit SortedSketchContainer(int32_t max_bins, MetaInfo const &info,
+  explicit SortedSketchContainer(int32_t max_bins, common::Span<FeatureType const> ft,
                                  std::vector<size_t> columns_size, bool use_group,
                                  int32_t n_threads)
-      : SketchContainerImpl{columns_size, max_bins, info.feature_types.ConstHostSpan(), use_group,
-                            n_threads} {
+      : SketchContainerImpl{columns_size, max_bins, ft, use_group, n_threads} {
     monitor_.Init(__func__);
-    sketches_.resize(info.num_col_);
+    sketches_.resize(columns_size.size());
     size_t i = 0;
     for (auto &sketch : sketches_) {
       sketch.sketch = &Super::sketches_[i];