feat(fast-make): allow shared cache

One may enable the shared cache by setting the following prior to
loading the fast-synthax-highlighting module

```sh
typeset -gA FAST_HIGHLIGHT
FAST_HIGHLIGHT[chroma-make-cache-global]=1
```

Shared cache item is kept for 1hours. Current design expose a "flaw",
where the same cached is used for any other makefile over the next hour.

Still to implement:
- parameterize caching timeout
- introduce 1 cache items per path

Author: burgesQ

.fast-make-targets

@@ -87,10 +87,23 @@ local -a TARGETS
     done
 }
 
-if [[ -z "${FAST_HIGHLIGHT[chroma-make-cache]}" || $(( EPOCHSECONDS - FAST_HIGHLIGHT[chroma-make-cache-born-at] )) -gt 7 ]]; then
-    .make-parseMakefile
-    FAST_HIGHLIGHT[chroma-make-cache-born-at]="$EPOCHSECONDS"
-    FAST_HIGHLIGHT[chroma-make-cache]="${(j:;:)TARGETS}"
+# Cache generated parsing for 1h per session or globally if configured.
+if [[ -n "${FAST_HIGHLIGHT[chroma-make-cache-global]}" ]]; then
+    : "${FAST_HIGHLIGHT[chroma-make-cache-file]:="/tmp/fast-highlight-make-cache"}"
+    : "${FAST_HIGHLIGHT[chroma-make-cache-born-at-file]:="/tmp/fast-highlight-make-cache-born-at"}"
+    if [[ ! -f ${FAST_HIGHLIGHT[chroma-make-cache-file]} || ! -f ${FAST_HIGHLIGHT[chroma-make-cache-born-at-file]} || $(( EPOCHSECONDS - $(<"${FAST_HIGHLIGHT[chroma-make-cache-born-at-file]}") )) -gt 3600 ]]; then
+        .make-parseMakefile
+        print -r -- "$EPOCHSECONDS" >| "${FAST_HIGHLIGHT[chroma-make-cache-born-at-file]}"
+        print -r -- "${(j:;:)TARGETS}" >| "${FAST_HIGHLIGHT[chroma-make-cache-file]}"
+    fi
+    FAST_HIGHLIGHT[chroma-make-cache]="$(<"${FAST_HIGHLIGHT[chroma-make-cache-file]}")"
+    FAST_HIGHLIGHT[chroma-make-cache-born-at]="$(<"${FAST_HIGHLIGHT[chroma-make-cache-born-at-file]}")"
+else
+    if [[ -z "${FAST_HIGHLIGHT[chroma-make-cache]}" || $(( EPOCHSECONDS - FAST_HIGHLIGHT[chroma-make-cache-born-at] )) -gt 3600 ]]; then
+        .make-parseMakefile
+        FAST_HIGHLIGHT[chroma-make-cache-born-at]="$EPOCHSECONDS"
+        FAST_HIGHLIGHT[chroma-make-cache]="${(j:;:)TARGETS}"
+    fi
 fi
 
 reply2=( "${(s:;:)FAST_HIGHLIGHT[chroma-make-cache]}" )