chore: Import defradb/errors for Join

[ChrisBQu]

Relevant issue(s)

Resolves #3334

Description

In many locations in the code base, we were importing the "errors" package in order to utilize the Join function. However, we now have this functionality as part of our own errors package. So throughout the codebase import statements, "errors" has been changed to "github.com/sourcenetwork/defradb/errors"

Tasks

• I made sure the code is well commented, particularly hard-to-understand areas.
• I made sure the repository-held documentation is changed accordingly.
• I made sure the pull request title adheres to the conventional commit style (the subset used in the project can be found in tools/configs/chglog/config.yml).
• I made sure to discuss its limitations such as threats to validity, vulnerability to mistake and misuse, robustness to invalidation of assumptions, resource requirements, ...

How has this been tested?

Specify the platform(s) on which this was tested:

• Windows

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.13%. Comparing base (65fa135) to head (45941ad).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3343      +/-   ##
===========================================
+ Coverage    78.10%   78.13%   +0.02%     
===========================================
  Files          388      388              
  Lines        35398    35398              
===========================================
+ Hits         27647    27655       +8     
+ Misses        6119     6110       -9     
- Partials      1632     1633       +1     

Flag	Coverage Δ
all-tests	78.13% <ø> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
client/definitions.go	75.63% <ø> (ø)
client/document.go	64.08% <ø> (ø)
datastore/prefix_query.go	83.78% <ø> (ø)
http/client_collection.go	45.45% <ø> (ø)
internal/db/description/collection.go	54.21% <ø> (ø)
internal/db/fetcher/indexer_iterators.go	74.95% <ø> (ø)
internal/db/fetcher/multi.go	74.14% <ø> (ø)
internal/db/view.go	64.42% <ø> (ø)
internal/request/graphql/schema/manager.go	88.46% <ø> (ø)
node/node.go	57.36% <ø> (ø)

... and 12 files with indirect coverage changes

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[fredcarle]

LGTM. Thanks for cleaning this up.