colexecbase: add more casts between native types and improve template

This commit introduces several casts between natively supported types,
mostly bytes-like.

This commit also cleans up things around BCEs because bytes-like vectors
don't support slicing.

Additionally, this commit refactors the cast template in order to use
the execgen rather than the text/template stuff as well as makes the
error for unsupported casts more descriptive.

Release note: None

pkg/sql/colexec/colexecbase/BUILD.bazel

@@ -22,16 +22,20 @@ go_library(
         "//pkg/sql/colexecerror",
         "//pkg/sql/colexecop",
         "//pkg/sql/colmem",  # keep
+        "//pkg/sql/lex",  # keep
         "//pkg/sql/pgwire/pgcode",
         "//pkg/sql/pgwire/pgerror",
         "//pkg/sql/rowenc",  # keep
         "//pkg/sql/sem/tree",  # keep
         "//pkg/sql/types",
+        "//pkg/util",  # keep
         "//pkg/util/duration",  # keep
         "//pkg/util/json",  # keep
         "//pkg/util/log",
+        "//pkg/util/uuid",  # keep
         "@com_github_cockroachdb_apd_v2//:apd",  # keep
         "@com_github_cockroachdb_errors//:errors",
+        "@com_github_lib_pq//oid",  # keep
     ],
 )