BLI: Bounds: Add basic functions

The overall goal is to be able to eventually replace the `BLI_rect.h` C-style API.
This only adds come basic functions and tests.

@@ -19,0 +24,4 @@
+  void translate(const T &offset);
+  void scale_from_center(const T &scale);
+
+  void resize(const T &new_size);

@@ -119,0 +120,4 @@
+}  // namespace bounds
+
+template<typename T, int Size>
+[[nodiscard]] inline bool less_or_equal_than(const VecBase<T, Size> &a, const VecBase<T, Size> &b)

@@ -119,0 +132,4 @@
+
+template<typename T> inline bool Bounds<T>::is_empty() const
+{
+  if (std::is_integral<T>::value || std::is_floating_point<T>::value) {

@@ -119,0 +174,4 @@
+  this->translate(offset);
+}
+
+template<typename T> void Bounds<T>::pad(const T &padding)

@@ -119,0 +134,4 @@
+
+}  // namespace detail
+
+template<typename T> inline bool Bounds<T>::is_empty() const