Rewrite all stdlib functions implemented in FunC to Tact

[i582]

Since we want to move away from FunC dependency, a major problem along the way is that we can't use FunC code in stdlib functions, so we have to start rewriting them to Tact.

• Rewrite contractAddressExt (__tact_compute_contract_address) in Tact #1763
• Rewrite Address.asSlice (__tact_address_to_slice) in Tact #1764
• Rewrite newAddress (__tact_create_address) in Tact #1765
• Rewrite Int.toString (__tact_int_to_string) in Tact #1780
• Rewrite Int.toFloatString (__tact_float_to_string) in Tact #1781

[Gusarich]

some of them will probably become less efficient because of that

[anton-trunov]

Let's create a plan with sub-issues for each function we want to migrate, so each of those functions would come with a gas benchmark

[novusnota]

some of them will probably become less efficient because of that

I'm guessing not yet, since the underlying implementation would still map to FunC for the time being, at least where it's more efficient than just asm (like in .storeUint() functions and such)