Show Create Tag and Edge

[darionyaphet]

nebula> show create tag player
===========================================
|                                 Command |
===========================================
| CREATE TAG player(name string, age int) |
-------------------------------------------
Got 1 rows (Time spent: 189/915 us)

nebula> show create edge serve
===================================================
|                                         Command |
===================================================
| CREATE EDGE serve(start_year int, end_year int) |
---------------------------------------------------
Got 1 rows (Time spent: 167/965 us)

[ayyt]

Support show create tag/edge xxx, show create space xxx SQL #439 has implement In pr #496

By the way, this is not the function I expected.

[dangleptr]

duplicate with #496 ?

[ayyt]

duplicate with #496 ?

Yeah, duplicate with #496, refer Issue #439 Support show create tag/edge xxx, show create space xxx SQL

This PR is also not what I expected because there is no intention to Issue PR #439

[dangleptr]

duplicate with #496 ?

Yeah, duplicate with #496, refer Issue #439 Support show create tag/edge xxx, show create space xxx SQL

This PR is also not what I expected because there is no intention to Issue PR #439

If so, please abandon it and give your review comments in #496 @darionyaphet