Add coins (UTXOs) tab and makes it view-only

[apogio]

GUI: Add coins tab and sets view-only mode

Adds Coins (UTXOs) tab at the top and:

• Removes selection checkboxes from the dialog
• Disables coin selection functionality
• Maintains UTXO viewing capabilities
• Removes all the information from the top area of the dialog.

The following pictures depict how the GUI would look like:

[DrahtBot]

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Conflicts

Reviewers, this pull request conflicts with the following ones:

• #815 (Bugfix on TransactionsView - Disable if privacy mode is set during wallet selection by pablomartin4btc)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

[hebasto]

cc @achow101 @Sjors

[apogio]

So, I've got 3 failed pipeline checks. I'll need to check them.

[apogio]

Pipeline issues should be fixed now.

[luke-jr]

Should probably only be available if advanced coin control is enabled in settings, and maybe only on a menu even then (if it made sense to do it as a tab, it should be within the main window, not a new window).

The SVG source for the new icon should also be included.

[apogio]

Should probably only be available if advanced coin control is enabled in settings, and maybe only on a menu even then (if it made sense to do it as a tab, it should be within the main window, not a new window).

The SVG source for the new icon should also be included.

Thanks for the comments! I will check soon!

[apogio]

So I've made the changes.

Specifically:

1. I added the .svg file, like discussed.
2. I set the coins tab to be in the same window and not open a new one.
3. I set the coins tab to be visible only if "coin control features" are enabled in the advanced options.

The way it works is:

When coin control features are disabled, then the "Coins" tab will be hidden, like in this picture:

Once the user enables coin control features, then the "Coins" tab will appear, like so:

If the user has the Coins tab enabled (i.e has coin control features enabled) and then disables it, the "Coins" tab will hide again and the user will be transferred to the "Overview" tab.

And lastly, here is the way that the coins tab will look like:

I kept the quantity and the amount visible, to be able to see some summaries easier. I also kept the tree mode and list mode, to facilitate UTXO viewing, especially for wallets with multiple UTXOs.