String: Mark move constructor & assignment op as `noexcept`

The Icinga DB code performs intensive operations on certain STL containers,
primarily on `std::vector<String>`. Specifically, it inserts 2-3 new elements
at the beginning of a vector containing thousands of elements. Without this commit,
all the existing elements would be unnecessarily copied just to accommodate the new
elements at the front. By making this change, the compiler is able to optimize STL
operations like `push_back`, `emplace_back`, and `insert`, enabling it to prefer the
move constructor over copy operations, provided it is guaranteed that no exceptions
will be thrown.

lib/base/string.cpp

@@ -33,7 +33,7 @@ String::String(const String& other)
 	: m_Data(other)
 { }
 
-String::String(String&& other)
+String::String(String&& other) noexcept
 	: m_Data(std::move(other.m_Data))
 { }
 
@@ -66,7 +66,7 @@ String& String::operator=(const String& rhs)
 	return *this;
 }
 
-String& String::operator=(String&& rhs)
+String& String::operator=(String&& rhs) noexcept
 {
 	m_Data = std::move(rhs.m_Data);
 	return *this;

lib/base/string.hpp

@@ -44,7 +44,7 @@ public:
 	String(std::string data);
 	String(String::SizeType n, char c);
 	String(const String& other);
-	String(String&& other);
+	String(String&& other) noexcept;
 
 #ifndef _MSC_VER
 	String(Value&& other);
@@ -56,7 +56,7 @@ public:
 	{ }
 
 	String& operator=(const String& rhs);
-	String& operator=(String&& rhs);
+	String& operator=(String&& rhs) noexcept;
 	String& operator=(Value&& rhs);
 	String& operator=(const std::string& rhs);
 	String& operator=(const char *rhs);