LibELF: Change TLS offset calculation

This changes the TLS offset calculation logic to be based on the
symbol's size instead of the total size of the TLS.

Because of this change, we no longer need to pipe "m_tls_size" to so
many functions.

Also, After this patch, the TLS data of the main program exists at the
"end" of the TLS block (Highest addresses).

This fixes a part of #6609.

Userland/Libraries/LibELF/DynamicObject.h

@@ -264,6 +264,7 @@ public:
 
     struct SymbolLookupResult {
         FlatPtr value { 0 };
+        size_t size { 0 };
         VirtualAddress address;
         unsigned bind { STB_LOCAL };
         const ELF::DynamicObject* dynamic_object { nullptr }; // The object in which the symbol is defined