Add .wasm file extension to wasm files

[webmaster128]

It would be nice if .was. files had a .wasm file extension on disk to make the file tree easier to understand.

Before:

$ l ~/.noisd/wasm/wasm/state/wasm/
b8cc8ae4201ee757a70c1e6d8b72c3afb94fc36ba95294ab0614011069de0fe5
cb7b021831dd908b673491288b7a76f7ae973b8c1586ce41d9a69cadab5202c7
ddaca2d1887555ebfe07a65ebec09fd3a159e78c3c429de9281187ac1780f5a0

After:

$ l ~/.noisd/wasm/wasm/state/wasm/
b8cc8ae4201ee757a70c1e6d8b72c3afb94fc36ba95294ab0614011069de0fe5.wasm
cb7b021831dd908b673491288b7a76f7ae973b8c1586ce41d9a69cadab5202c7.wasm
ddaca2d1887555ebfe07a65ebec09fd3a159e78c3c429de9281187ac1780f5a0.wasm

To allow a smooth transition, the cache should store with .wasm file extension and try loading .wasm first and then without the .wasm. Ever new node and ever node that goes through state sync will only have the new format. The old format needs to be supported for a while to not disrupt long running machines.