wallet: Avoid translating RPC errors when creating txs

Also, mark feebumper bilingual_str as Untranslated

They are technical and have previously not been translated either.
It is questionable whether they can even appear in the GUI.

src/interfaces/wallet.cpp

@@ -219,7 +219,7 @@ public:
         bool sign,
         int& change_pos,
         CAmount& fee,
-        std::string& fail_reason) override
+        bilingual_str& fail_reason) override
     {
         LOCK(m_wallet->cs_wallet);
         CTransactionRef tx;
@@ -248,7 +248,7 @@ public:
     }
     bool createBumpTransaction(const uint256& txid,
         const CCoinControl& coin_control,
-        std::vector<std::string>& errors,
+        std::vector<bilingual_str>& errors,
         CAmount& old_fee,
         CAmount& new_fee,
         CMutableTransaction& mtx) override
@@ -258,7 +258,7 @@ public:
     bool signBumpTransaction(CMutableTransaction& mtx) override { return feebumper::SignTransaction(*m_wallet.get(), mtx); }
     bool commitBumpTransaction(const uint256& txid,
         CMutableTransaction&& mtx,
-        std::vector<std::string>& errors,
+        std::vector<bilingual_str>& errors,
         uint256& bumped_txid) override
     {
         return feebumper::CommitTransaction(*m_wallet.get(), txid, std::move(mtx), errors, bumped_txid) ==