repart: Allow overriding fstype per partition designator

$SYSTEMD_REPART_OVERRIDE_FSTYPE is too invasive. Often you want to
override the fstype only for a specific designator, so let's support
that as well.

src/shared/gpt.c

@@ -339,6 +339,18 @@ bool gpt_partition_type_knows_no_auto(GptPartitionType type) {
                       PARTITION_SWAP);
 }
 
+bool gpt_partition_type_has_filesystem(GptPartitionType type) {
+        return IN_SET(type.designator,
+                      PARTITION_ROOT,
+                      PARTITION_USR,
+                      PARTITION_HOME,
+                      PARTITION_SRV,
+                      PARTITION_ESP,
+                      PARTITION_XBOOTLDR,
+                      PARTITION_TMP,
+                      PARTITION_VAR);
+}
+
 bool gpt_header_has_signature(const GptHeader *p) {
         assert(p);
 

src/shared/gpt.h

@@ -72,6 +72,7 @@ const char* gpt_partition_type_mountpoint_nulstr(GptPartitionType type);
 bool gpt_partition_type_knows_read_only(GptPartitionType type);
 bool gpt_partition_type_knows_growfs(GptPartitionType type);
 bool gpt_partition_type_knows_no_auto(GptPartitionType type);
+bool gpt_partition_type_has_filesystem(GptPartitionType type);
 
 typedef struct {
         uint8_t partition_type_guid[16];