Minor UX Updates on Layer Content Browser, Value Edits and Graph Viewers

[chrizzFTD]

• Ability to open images (when supported by Qt) in layer content browser
• Layer content browser no longer fails when valid older usda content doesn't roundtrip to crate (due to new USD versions)
• Other minor UX improvements in layer content browser (copy identifiers, tab management, line count, zoom in / out)
• Support for editing string and token values in the experimental value editor
• Fast edit of some value types through context menu in the prim browser in USDView
• Minor fix on Display Color Editor buttons
• Minor UX fix for bidirectional connection edges offsetting only when not using splines in graph viewers
• Enable Python-3.12 in CI

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 93.92265% with 11 lines in your changes missing coverage. Please review.

Project coverage is 92.81%. Comparing base (756935c) to head (cdbae5c). Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
grill/views/description.py	91.07%	10 Missing :warning:
grill/views/_attributes.py	75.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #39 +/- ## =========================================== + Coverage 92.63% 92.81% +0.17% =========================================== Files 17 17 Lines 3665 3826 +161 =========================================== + Hits 3395 3551 +156 - Misses 270 275 +5 ``` | [Files with missing lines](https://app.codecov.io/gh/thegrill/grill/pull/39?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill) | Coverage Δ | | |---|---|---| | [grill/usd/\_\_init\_\_.py](https://app.codecov.io/gh/thegrill/grill/pull/39?src=pr&el=tree&filepath=grill%2Fusd%2F__init__.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill#diff-Z3JpbGwvdXNkL19faW5pdF9fLnB5) | `100.00% <100.00%> (ø)` | | | [grill/views/\_graph.py](https://app.codecov.io/gh/thegrill/grill/pull/39?src=pr&el=tree&filepath=grill%2Fviews%2F_graph.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill#diff-Z3JpbGwvdmlld3MvX2dyYXBoLnB5) | `76.78% <100.00%> (ø)` | | | [tests/test\_usd.py](https://app.codecov.io/gh/thegrill/grill/pull/39?src=pr&el=tree&filepath=tests%2Ftest_usd.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill#diff-dGVzdHMvdGVzdF91c2QucHk=) | `100.00% <100.00%> (ø)` | | | [tests/test\_views.py](https://app.codecov.io/gh/thegrill/grill/pull/39?src=pr&el=tree&filepath=tests%2Ftest_views.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill#diff-dGVzdHMvdGVzdF92aWV3cy5weQ==) | `100.00% <100.00%> (+0.17%)` | :arrow_up: | | [grill/views/\_attributes.py](https://app.codecov.io/gh/thegrill/grill/pull/39?src=pr&el=tree&filepath=grill%2Fviews%2F_attributes.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill#diff-Z3JpbGwvdmlld3MvX2F0dHJpYnV0ZXMucHk=) | `96.00% <75.00%> (+0.05%)` | :arrow_up: | | [grill/views/description.py](https://app.codecov.io/gh/thegrill/grill/pull/39?src=pr&el=tree&filepath=grill%2Fviews%2Fdescription.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill#diff-Z3JpbGwvdmlld3MvZGVzY3JpcHRpb24ucHk=) | `93.09% <91.07%> (+0.20%)` | :arrow_up: | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/thegrill/grill/pull/39/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=thegrill)