all: Add receive only folder type (#5027)

Adds a receive only folder type that does not send changes, and where the user can optionally revert local changes. Also changes some of the icons to make the three folder types distinguishable.

lib/protocol/protocol_test.go

@@ -423,6 +423,7 @@ func TestIsEquivalent(t *testing.T) {
 		b         FileInfo
 		ignPerms  *bool // nil means should not matter, we'll test both variants
 		ignBlocks *bool
+		ignFlags  uint32
 		eq        bool
 	}
 	cases := []testCase{
@@ -491,6 +492,17 @@ func TestIsEquivalent(t *testing.T) {
 			b:  FileInfo{LocalFlags: FlagLocalUnsupported},
 			eq: true,
 		},
+		{
+			a:  FileInfo{LocalFlags: 0},
+			b:  FileInfo{LocalFlags: FlagLocalReceiveOnly},
+			eq: false,
+		},
+		{
+			a:        FileInfo{LocalFlags: 0},
+			b:        FileInfo{LocalFlags: FlagLocalReceiveOnly},
+			ignFlags: FlagLocalReceiveOnly,
+			eq:       true,
+		},
 
 		// Difference in blocks is not OK
 		{
@@ -588,10 +600,10 @@ func TestIsEquivalent(t *testing.T) {
 					continue
 				}
 
-				if res := tc.a.IsEquivalent(tc.b, ignPerms, ignBlocks); res != tc.eq {
+				if res := tc.a.isEquivalent(tc.b, ignPerms, ignBlocks, tc.ignFlags); res != tc.eq {
 					t.Errorf("Case %d:\na: %v\nb: %v\na.IsEquivalent(b, %v, %v) => %v, expected %v", i, tc.a, tc.b, ignPerms, ignBlocks, res, tc.eq)
 				}
-				if res := tc.b.IsEquivalent(tc.a, ignPerms, ignBlocks); res != tc.eq {
+				if res := tc.b.isEquivalent(tc.a, ignPerms, ignBlocks, tc.ignFlags); res != tc.eq {
 					t.Errorf("Case %d:\na: %v\nb: %v\nb.IsEquivalent(a, %v, %v) => %v, expected %v", i, tc.a, tc.b, ignPerms, ignBlocks, res, tc.eq)
 				}
 			}