compute() breaks schemas in dbplyr 2.2.0

[baileych]

The addition of an unconditional call to unname() in compute.tbl_sql() added in #793 breaks use of schemas and catalogs, since both dbplyr::in_schema() and dbplyr::in_catalog() rely on names to identify the parts of the table identifier. Once the names are removed, a schema-qualified table name always renders as "NULL.NULL" (and similarly for catalog-schema-qualified tables).

require(dplyr)
require(RSQLite)
db <- DBI::dbConnect(SQLite(), ':memory:')
schematized <- dbplyr::in_schema('test', 'this')
# Create a table to select and compute
mtcars %>% slice_head(n = 5) %>% copy_to(db, ., name = 'this')
thistbl <- tbl(db, 'this')
#Bang
thistbl %>% compute(name = schematized)

yields Error: near "NULL": syntax error

A minimal fix would be to preserve names in cases we know they'll be needed:

 if (!any(class(name) %in% c('dbplyr_schema', 'dbplyr_catalog'))) name <- unname(name)