remove export choices on export argument

[jmaslek]

See below. After changing the choices, we get something like in #3508. The reason is that the refactoring for choices forces the input to be a file type.

By removing this we have the following:

2022 Nov 29, 11:56 (🦋) /stocks/ $ load aapl --export aapl1.csv

Loading Daily data for AAPL with starting period 2019-11-25.

Company:  Apple Inc.
Exchange: NASDAQ/NMS (GLOBAL MARKET)
Currency: USD

                                          AAPL Performance                                          
┏━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━┓
┃ 1 Day   ┃ 1 Week  ┃ 1 Month ┃ 1 Year ┃ YTD     ┃ Volatility (1Y) ┃ Volume (10D avg) ┃ Last Price ┃
┡━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━┩
│ -4.53 % │ -4.67 % │ -0.24 % │ -7.5 % │ -20.3 % │ 35.48 %         │ 76.42 M          │ 144.22     │
└─────────┴─────────┴─────────┴────────┴─────────┴─────────────────┴──────────────────┴────────────┘

Saved file: /Users/james/OpenBBUserData/exports/aapl1.csv

2022 Nov 29, 11:56 (🦋) /stocks/ $ load aapl --export csv

Loading Daily data for AAPL with starting period 2019-11-25.

Company:  Apple Inc.
Exchange: NASDAQ/NMS (GLOBAL MARKET)
Currency: USD

                                          AAPL Performance                                          
┏━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━┓
┃ 1 Day   ┃ 1 Week  ┃ 1 Month ┃ 1 Year ┃ YTD     ┃ Volatility (1Y) ┃ Volume (10D avg) ┃ Last Price ┃
┡━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━┩
│ -4.53 % │ -4.67 % │ -0.24 % │ -7.5 % │ -20.3 % │ 35.48 %         │ 76.42 M          │ 144.22     │
└─────────┴─────────┴─────────┴────────┴─────────┴─────────────────┴──────────────────┴────────────┘

Saved file: /Users/james/OpenBBUserData/exports/20221129_115839_OpenBBTerminal_openbb_terminal_load.csv

2022 Nov 29, 11:58 (🦋) /stocks/ $ load aapl --export cfgfgsfg

Filename 'cfgfgsfg' provided is not valid!
Loading Daily data for AAPL with starting period 2019-11-25.

Since this is the base controller, it will port.

Note: Fixes #3508

[Chavithra]

Looks ok to me.