Improve BMA `/tx/history/:pubkey/pending`, `/tx/history/:pubkey/blocks/:from/:to` and `/tx/history/:pubkey/times/:from/:to`

I thhink we cn optimize the response time of BMA /tx/history/:pubkey/pending

In Duniter dev branch, i can see that:

• in transactions.ts the pubkey's full history is laoded (including sending and received), then filtered :

  async getPendingForPubkey(req: any): Promise<HttpTxHistory> {
    const pubkey = await ParametersService.getPubkeyP(req);
    return this.getFilteredHistory(pubkey, function (res: any) {
      const histo = res.history;
      Underscore.extend(histo, { sent: [], received: [] });
      return res;
    });
  }
  
  private async getFilteredHistory(
    pubkey: string,
    filter: any
    ): Promise<HttpTxHistory> {
      let history = await this.server.dal.getTransactionsHistory(pubkey);
      let result = {
        currency: this.conf.currency,
        pubkey: pubkey,
        history: {
          sending: history.sending.map(dbtx2HttpTxOfHistory),
          received: history.received.map(dbtx2HttpTxOfHistory),
          sent: history.sent.map(dbtx2HttpTxOfHistory),
          pending: history.pending.map(dbtx2HttpTxOfHistory),
        },
      };
    return filter(result);
    }
  }

• there is not DAL function to get only pending TX, by pubkey