Use static maps to convert input events

This improves readability (hopefully).

PR #2831 <https://github.com/Genymobile/scrcpy/pull/2831>

app/src/util/intmap.c

@@ -0,0 +1,13 @@
+#include "intmap.h"
+
+const struct sc_intmap_entry *
+sc_intmap_find_entry(const struct sc_intmap_entry entries[], size_t len,
+                     int32_t key) {
+    for (size_t i = 0; i < len; ++i) {
+        const struct sc_intmap_entry *entry = &entries[i];
+        if (entry->key == key) {
+            return entry;
+        }
+    }
+    return NULL;
+}