perf: snapshot load improvement roadmap

[mmastrac]

• Avoid serializing module globals for modules that won't be imported using import "module" syntax. These add extra overhead to the snapshot. We may be able to avoid serializing any module global at all, however v8 seems not to cache module loads (?). This may require further investigation.
• Experiment with minifying sources to reduce the # of strings stored in the snapshot. These show up as roots:

[deno 1.43.0]  Encoding root 309:0x0a3c18886979 <String[8]: #weekInfo>
[deno 1.43.0]  Encoding root 311:0x0a3c188869a9 <String[12]: #yearsDisplay>
[deno 1.43.0]  Encoding root 535:0x0a3c18888261 <String[11]: #Reflect.get>
[deno 1.43.0]  Encoding root 584:0x0a3c18888801 <String[6]: #symbol>
[deno 1.43.0]  Encoding root 549:0x0a3c18888411 <String[6]: #script>
[deno 1.43.0]  Encoding root 390:0x0a3c18887261 <String[5]: #Error>
[deno 1.43.0]  Encoding root 500:0x0a3c18887eb9 <String[4]: #NFKD>

• Add computed module types to extensions. This will help us avoid partially-constructed code showing up in the snapshot (see FsStat and buildAllowedFlags in Deno).
• Add true lazy module that are only evaluated on-demand (versus lazy-loaded ESM).
• Add lazy ops that are instantiated only on first use