feat: typed storage interface

[wzc520pyfm]

Refer: #508

We can improve the ts type as follows:

type TestObjType = {
  a: number;
  b: boolean;
};
type MyStorage = {
  foo: string;
  baz: TestObjType;
};
const storage = createStorage<MyStorage>();
await storage.getItem("foo"); // => <string>
await storage.getItem("baz"); // => <TestObjType>
storage.setItem("foo", "val"); // Check ok
storage.setItem("foo", 123); // TS error

and get hints as you type:

[codecov]

Codecov Report

Attention: Patch coverage is 94.44444% with 1 line in your changes missing coverage. Please review.

Project coverage is 62.93%. Comparing base (4d61c78) to head (4d6d13b).
Report is 122 commits behind head on main.

Files with missing lines	Patch %	Lines
src/storage.ts	94.44%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #509      +/-   ##
==========================================
- Coverage   65.05%   62.93%   -2.12%     
==========================================
  Files          39       39              
  Lines        4055     3343     -712     
  Branches      487      579      +92     
==========================================
- Hits         2638     2104     -534     
+ Misses       1408     1236     -172     
+ Partials        9        3       -6     

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[danielroe]

This is really nice to see!

I wonder if we could support extracting keys with : - so having a namespace:child would get the right types with a base of namespace and a key of child....

[pi0]

❤️