rust-index: add fast-path for getting a list of all heads as nodes
This avoids a lot of back-and-forth between Python and Rust. We forgo adding
a fast-path in the `filteredchangelog` case yet. If it shows up in profiling,
we might add the variant with a filter.
BasedOnStyle: LLVM
IndentWidth: 8
UseTab: ForIndentation
BreakBeforeBraces: Linux
AllowShortIfStatementsOnASingleLine: false
IndentCaseLabels: false
AllowShortBlocksOnASingleLine: false
AllowShortFunctionsOnASingleLine: false
IncludeCategories:
- Regex: '^<'
Priority: 1
- Regex: '^"'
Priority: 2