draft: drop table implementation

[someshkoli]

Closes #894, duplicate, had picked it up over weekend, didn't realise a pr was raised post that

has

• schema update for deleted table
• all statement and instructions wiring

missing

• destroy table implemenattion
• table dependency clearance, requires temporary table for storing intermediatery results
  depends on Add support for OpenEphemeral bytecode #768 Add support for delete row #785

limbo> 
limbo>  create table temp(a int, b int);
        insert into temp values(1,1);
        insert into temp values(2,2);
limbo> explain drop table temp;
addr  opcode             p1    p2    p3    p4             p5  comment
----  -----------------  ----  ----  ----  -------------  --  -------
0     Init               0     18    0                    0   Start at 18
1     Null               0     1     0                    0   r[1]=NULL
2     OpenWriteAsync     0     1     0                    0   
3     OpenWriteAwait     0     0     0                    0   
4     RewindAsync        0     0     0                    0   
5     RewindAwait        0     15    0                    0   Rewind table sqlite_schema
6       Column           0     2     1                    0   r[1]=sqlite_schema.tbl_name
7       Ne               1     2     13                   0   if r[1]!=r[2] goto 13
8       Column           0     0     3                    0   r[3]=sqlite_schema.type
9       Eq               3     4     13                   0   if r[3]==r[4] goto 13
10      RowId            0     5     0                    0   r[5]=sqlite_schema.rowid
11      DeleteAsync      0     0     0                    0   
12      DeleteAwait      0     0     0                    0   
13    NextAsync          0     0     0                    0   
14    NextAwait          0     6     0                    0   
15    DestroyAsync       2     2     0                    0   
16    DestroyAwait       2     2     0                    0   
17    Halt               0     0     0                    0   
18    Transaction        0     0     0                    0   
19    String8            0     2     0     temp           0   r[2]='temp'
20    String8            0     4     0     trigger        0   r[4]='trigger'
21    Goto               0     2     0                    0