Add tokyo-moon theme variant (#710)

Closes #702. I was wrong in thinking the "night" and "storm" variants
should be much different — they're not. It's the divergent "moon"
variant between them that was missing. Added.

I have slight doubts about the darker gray `#828bb8` being used for e.g.
`ls` columns, but I think that basically correct. The high-contrast
foreground color `#c8d3f5` is the bright variant of that and should show
up in most other contexts I reckon.

themes/nu-themes/tokyo-moon.nu

@@ -0,0 +1,82 @@
+export def main [] { return {
+    separator: "#828bb8"
+    leading_trailing_space_bg: { attr: "n" }
+    header: { fg: "#c3e88d" attr: "b" }
+    empty: "#82aaff"
+    bool: {|| if $in { "#86e1fc" } else { "light_gray" } }
+    int: "#828bb8"
+    filesize: {|e|
+        if $e == 0b {
+            "#828bb8"
+        } else if $e < 1mb {
+            "#86e1fc"
+        } else {{ fg: "#82aaff" }}
+    }
+    duration: "#828bb8"
+    date: {|| (date now) - $in |
+        if $in < 1hr {
+            { fg: "#ff757f" attr: "b" }
+        } else if $in < 6hr {
+            "#ff757f"
+        } else if $in < 1day {
+            "#ffc777"
+        } else if $in < 3day {
+            "#c3e88d"
+        } else if $in < 1wk {
+            { fg: "#c3e88d" attr: "b" }
+        } else if $in < 6wk {
+            "#86e1fc"
+        } else if $in < 52wk {
+            "#82aaff"
+        } else { "dark_gray" }
+    }
+    range: "#828bb8"
+    float: "#828bb8"
+    string: "#828bb8"
+    nothing: "#828bb8"
+    binary: "#828bb8"
+    cellpath: "#828bb8"
+    row_index: { fg: "#c3e88d" attr: "b" }
+    record: "#828bb8"
+    list: "#828bb8"
+    block: "#828bb8"
+    hints: "dark_gray"
+    search_result: { fg: "#ff757f" bg: "#828bb8" }
+
+    shape_and: { fg: "#c099ff" attr: "b" }
+    shape_binary: { fg: "#c099ff" attr: "b" }
+    shape_block: { fg: "#82aaff" attr: "b" }
+    shape_bool: "#86e1fc"
+    shape_custom: "#c3e88d"
+    shape_datetime: { fg: "#86e1fc" attr: "b" }
+    shape_directory: "#86e1fc"
+    shape_external: "#86e1fc"
+    shape_externalarg: { fg: "#c3e88d" attr: "b" }
+    shape_filepath: "#86e1fc"
+    shape_flag: { fg: "#82aaff" attr: "b" }
+    shape_float: { fg: "#c099ff" attr: "b" }
+    shape_garbage: { fg: "#FFFFFF" bg: "#FF0000" attr: "b" }
+    shape_globpattern: { fg: "#86e1fc" attr: "b" }
+    shape_int: { fg: "#c099ff" attr: "b" }
+    shape_internalcall: { fg: "#86e1fc" attr: "b" }
+    shape_list: { fg: "#86e1fc" attr: "b" }
+    shape_literal: "#82aaff"
+    shape_match_pattern: "#c3e88d"
+    shape_matching_brackets: { attr: "u" }
+    shape_nothing: "#86e1fc"
+    shape_operator: "#ffc777"
+    shape_or: { fg: "#c099ff" attr: "b" }
+    shape_pipe: { fg: "#c099ff" attr: "b" }
+    shape_range: { fg: "#ffc777" attr: "b" }
+    shape_record: { fg: "#86e1fc" attr: "b" }
+    shape_redirection: { fg: "#c099ff" attr: "b" }
+    shape_signature: { fg: "#c3e88d" attr: "b" }
+    shape_string: "#c3e88d"
+    shape_string_interpolation: { fg: "#86e1fc" attr: "b" }
+    shape_table: { fg: "#82aaff" attr: "b" }
+    shape_variable: "#c099ff"
+
+    background: "#222436"
+    foreground: "#c8d3f5"
+    cursor: "#c8d3f5"
+}}