feat: enable wasmtime caching

[zshipko]

Alternate to: #596 without support for manually compiling/loading native code

• Enables wasmtime caching: https://docs.wasmtime.dev/cli-cache.html
• Adds EXTISM_CACHE_CONFIG and PluginBuilder::with_cache_config to determine where to load a custom cache configuration from
• Adds PluginBuilder::with_cache_disabled to disable the cache when initializing a plugin
  • Setting EXTISM_CACHE_CONFIG="" will also disable caching

Performance

With caching:

create/create_plugin    time:   [2.9079 ms 2.9139 ms 2.9200 ms]                                  
                        change: [+3.2677% +3.6399% +3.9766%] (p = 0.00 < 0.20)
                        Change within noise threshold.

Compared to main:

create/create_plugin    time:   [26.089 ms 26.498 ms 26.923 ms]                                 
                        change: [+0.1729% +2.0868% +4.1337%] (p = 0.04 < 0.20)
                        Change within noise threshold.