[VSP] save last used VSP host

[bgptr]

This update saves the last used VSP host to config after a successful ticket purchase on the new VSP page and sets the VSPSelects when the user arrives next time.
Closes #2763

[vctt94]

Thanks for this PR.

The vsp should be a wallet config and not a global config, as each wallet can have different vsps selected, as default.

[bgptr]

Thank you for the review.
I moved the vsp_host param to the wallet config.

[degeri]

can we have this as an optional clickable setting ? worried about centralization risks here. We want people to feel like they can choose any VSP they want.

[vctt94]

I think that's a valid point @degeri. Maybe we can have a checkbox near the ticket purchase area saying use default. What do you think @bgptr ?

[bgptr]

@vctt94 @degeri Sure thing, I have added the checkbox.

[jholdstock]

I've tried out the checkbox, I like the idea but it needs refining. I suggest

• Checkbox label should read "Always use this VSP"
• If no VSP is selected (ie. the dropdown says "Select VSP...") the checkbox should be hidden/deactivated. When a VSP is selected, checkbox appears/activates.
• When the checkbox is checked, the dropdown is deactivated to indicate that the value can not be changed. Checkbox must be unchecked again before dropdown value can change.

[bgptr]

@jholdstock I like your suggestions. I've implemented them.

[jholdstock]

Looking better but it seems like the selected vsp and checkbox are resetting when I closed/reopen decrediton.

Edit: Actually, I dont even need to restart decrediton. Just opening a new tab resets the values.

[bgptr]

@jholdstock You are right. Probably it's because I saved the VSP host only after successful ticket purchasing.

I revamped (and also cleaned up) the code to save immediately after clicking on the checkbox.
It's more user-friendly now. Thank you.

[vctt94]

needs rebase

[bgptr]

rebased

[vctt94]

I think that's a good start and we can iterate from here. Thanks @bgptr