Show erased terms on hover

[BinderDavid]

We want to display on hover which parts of the program are erased.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 101 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
lang/lsp/src/hover.rs	0.00%	55 Missing ⚠️
lang/driver/src/info/collect.rs	0.00%	46 Missing ⚠️

Files with missing lines	Coverage Δ
lang/driver/src/info/data.rs	0.00% <ø> (ø)
lang/driver/src/info/collect.rs	0.00% <0.00%> (ø)
lang/lsp/src/hover.rs	0.00% <0.00%> (ø)