[Major Feature]: add wildcard paths to allow HTML5-based routing.

[giac-mysten]

At the moment, HTML5-based routing probably does not work, because the routing of Walrus Sites requires an exact match of the URL path on the list of paths that are in the Sui object for the site.

A bit of design may be needed, but this would be great to enable existing JS tooling to be used with walrus sites.

Designs

Another default 404.html

Currently, if the portal/SW do not find a path, they revert to /404.html if it exists.

https://github.com/MystenLabs/walrus-sites/blob/9aad845f30a1e33f0aa4998c6b8a54b84f63b232/portal/src/walrus-sites-sw.ts#L287-L293

As a first step, we may want to allow setting a /walrus-sites-default.html, which, if it exists, gets loaded when no other path is found.

Pros:

• Very simple
• Allows for simple one page apps
• Only requires modifying the SW/portal logic

Cons:

• Does not fully capture the full potential of HTML5-based routing
• Introduces more "special files" (the default) that are Walrus sites specific

Contract-side defaults

We could achieve something similar to the above, but without special files, by adding a field in the Site object on chain that specifies the default Resource for the site

Pros / cons :

• Same as above, except it requires modifying both SW/portal and contracts
• Does not require special files

Wildcard paths

One possible solution would be to allow "wildcard" paths for resources. I.e., /view/* points to blob id asdf..., so that the root of the path determines what resources are loaded, and within those resources there is the code to interpret the rest of the url.

Pros:

• Does not require contract changes (except see cons below)
• Flexible: we can specify many different default resources

Cons:

• it requires checking that any prefix of the path exists as a wildcalrd path in the service workers
• we may need to enforce that there are no conflicting wildcard paths (in Move?)

[rjs-mysten]

If we go with wildcard paths, we should probably use a syntax similar to nginx rewrite rules

As for the con, we don't enforce that there are no conflicting wildcard paths, we just define that we will process rules in order and go to the first match. later, we can use a trie.