This changes the type for the sorted pattern table from
`vim.filetype.mapping[]` to `vim.filetype.mapping.sorted[]`
E.g. instead of:
```lua
{
{ ['/debian/changelog$'] = {'debchangelog', { parent = '/debian/' } },
{ ['%.git/'] = { detect.git , { parent = 'git/', priority = -1 } },
}
```
It is now:
```lua
{
{ '/debian/, '/debian/changelog$', 'debchangelog' },
{ 'git/' , '%.git/' , detect.git , -1 },
}
```
Overall this should roughly cut the amount of tables used by 3, and
replaces lots of hash indexes with array indexes.
ff575b3886