internal: simplify the removal of dulicate workspaces.
### Summary:
Refactoring the duplicate removal process for `workspaces` in `fetch_workspaces`.
### Changes Made:
Replaced `[].iter().enumerate().skip(...).filter_map(...)` with a more concise `[i+1..].positions(...)` provided by `itertools`, which enhances clarity without changing functionality
### Impact:
This change aims to enhance the duplicate removal process for `workspaces`. This change has been tested on my machine.
Please review and provide feedback. Thanks!
fix: Dedup duplicate crates with differing origins in CrateGraph construction
Partially fixes#15656 . Until now the condition for deduplication in crate graphs were the strict equality of two crates. One problem that arises from this is that in certain conditions when we see the same crate having different `CrateOrigin`s the first occurrence would be kept. This approach however results in some unwanted results such as making renaming forbidden as this has been recently only made available for local crates. The given example in #15656 can still not be resolved with this PR as that involves taking inconsistencies between dependencies into consideration. This will be addressed in a future PR.
Make data reflect a case where dev deps are existent.
base-db::CrateGraph::extend now adds dev dependencies for a crate
in case of its upgrading from a CrateOrigin::Lib kind of a crate to a
CrateOrigin::Local one.
Partially fixes#15656 . When a crate graph is extended which is the case when new workspaces are added to the project
the rules for deduplication were too strict. One problem that arises from this is that in certain conditions
when we see the same crate having different `CrateOrigin`s the first form would be maintained. This approach however
results in some unwanted results such as making renaming forbidden as this has been recently only made available for
local crates. The given example in #15656 can still not be resolved with this PR as that involves taking inconsistencies
between dependencies into consideration. This will be addressed in a future PR.
