Several Deeplink improvements

[snappdevelopment]

I have been using the deeplink feature recently and found a few issues/inconveniences.
I want to add the following fixes:

• Deleting the value of a variable on the left side should show the placeholder in the deeplink again instead of an empty string. Otherwise the deeplink looks broken.
• Variables on the left side which have auto complete values should use the first value as the default. This is for convenience, because you need to choose a value anyway.
• Very long deeplinks should be shown as multiline instead of being crushed at the end of the line.
• The variable view on the left should be scrollable. It was also changed from a FlowRow to a LazyColumn, because it is fast to read when each variable has its own line
• The values of the variables on the left should be multiline for long values
• The auto complete values in the dropdown menu should use the full width to be easily selectable

[rteyssandier]

Since now that variable are a column, you should rework a bit the UI to take advantage of the full line

[snappdevelopment]

Since now that variable are a column, you should rework a bit the UI to take advantage of the full line

I changed it a bit to use the full width for the variables