Add caching for thumbnails based and freedesktop.org spec

Cargo.lock

@@ -1507,6 +1507,7 @@ dependencies = [
  "libc",
  "libcosmic",
  "log",
+ "md-5",
  "mime_guess",
  "notify-debouncer-full",
  "notify-rust",
@@ -1514,6 +1515,7 @@ dependencies = [
  "open",
  "ordermap",
  "paste",
+ "png",
  "procfs",
  "recently-used-xbel",
  "regex",
@@ -4570,6 +4572,16 @@ dependencies = [
  "rayon",
 ]
 
+[[package]]
+name = "md-5"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d89e7ee0cfbedfc4da3340218492196241d89eefb6dab27de5df917a6d2e78cf"
+dependencies = [
+ "cfg-if",
+ "digest",
+]
+
 [[package]]
 name = "memchr"
 version = "2.7.5"