SignTool functionality complete

Last set of Signing issues required in Arcade so we can call Signing to be complete

# Recently Triaged Issues

All issues in this section should be triaged by the v-team into one of their business objectives or features.

- [x] https://github.com/dotnet/arcade/issues/1000
- [x] https://github.com/dotnet/arcade/issues/1295
- [x] https://github.com/dotnet/arcade/issues/1919
- [x] https://github.com/dotnet/arcade/issues/1494
- [x] https://github.com/dotnet/arcade/issues/1957
- [x] https://github.com/dotnet/arcade/issues/1370
- [x] https://github.com/dotnet/arcade/issues/2177
- [x] https://github.com/dotnet/arcade/issues/2283
- [x] https://github.com/dotnet/arcade/issues/2852
- [x] https://github.com/dotnet/arcade/issues/2888
- [x] https://github.com/dotnet/arcade/issues/2915
- [ ] https://github.com/dotnet/arcade/issues/412
- [ ] https://github.com/dotnet/arcade/issues/3651
- [ ] https://github.com/dotnet/arcade/issues/3762
- [ ] https://github.com/dotnet/arcade/issues/5234
- [ ] https://github.com/dotnet/arcade/issues/5939
- [ ] https://github.com/dotnet/arcade/issues/7621
- [x] https://github.com/dotnet/arcade/issues/7945