feat(linux): implement custom user data path

[lucasfernog]

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Documentation
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes. Issue #___
• No

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix: #xxx[,#xxx], where "xxx" is the issue number)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

We spotted the need for this on tauri-apps/tauri#1551

[wusyong]

LGTM!
Could you also help updating user_data_path in WebViewBuilder to with_user_data_path and updating its doc?

Btw, should we take this chance to rename the method name? I feel like with_storage_path or with_data_directory is easier for user to understand.

[lucasfernog]

Sounds good, I guess i'll go with with_data_directory.