Include paths need to be prefixed with the working directory and
normalized before being added to the merkle tree. Otherwise, invalid CAS
`Directory` messages with `..` entries may be generated.

This adds the configuration option `RECC_KEEPALIVE_TIME`. By default,
keepalive pings remain disabled.

If the path of a dependency contains `..` segments before normalization,
we need to ensure that the directories preceding the `..` exist in the
merkle tree. Otherwise, the OS will fail to resolve the non-normalized
path during action execution with `ENOENT`.

Errors from the dependencies command should only be visible in recc
logs, not stderr.

The behavior depends on whether `RECC_NO_PATH_REWRITE` is set.

Do not modify path arguments at all if `RECC_NO_PATH_REWRITE` is set.
This reduces differences between local and remote execution.

This makes it possible to unset a platform property from the recc config
file by setting an empty environment variable.

Reduce differences between local and remote execution.

This makes `evaluate_config_locations()` idempotent.

An optional salt value to place the `Action` into a separate cache
namespace.

jinja2

This uses batching for small files to make the download more efficient
and streams large files to disk to reduce peak memory usage.

This allows users of `ExecutionContext` to retrieve the action digest
after execution.

    recc/test/deps.t.cpp:90:32: warning: result of comparison against a string literal is unspecified (use an explicit string comparison function instead) [-Wstring-compare]

The `IMPORTED_TARGET` functionality of CMake `pkg_check_modules()`
doesn't support static linking. Pass `--static` to pkg-config to get the
right linker flags.

https://gitlab.kitware.com/cmake/cmake/-/issues/21714

These are new dependencies of gRPC with Debian 11.

Sphinx 3.x is not compatible with Python 3.10:

    ImportError: cannot import name 'Union' from 'types' (/usr/local/lib/python3.10/types.py)

This allows use of recc logic in other applications.