The config value `core.sparseCheckout` is parsed in
`git_default_core_config()` and stored globally in
`core_apply_sparse_checkout`. This could cause it to be overwritten
by another repository when different Git repositories run in the same
process.

Move the parsed value into `struct repo_config_values` in the_repository
to retain current behaviours and move towards libifying Git.

Suggested-by: Phillip Wood <phillip.wood123@gmail.com>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Signed-off-by: Olamide Caleb Bello <belkid98@gmail.com>

…lues`

The config value `branch.autoSetupMerge` is parsed in
`git_default_branch_config()` and stored in the global variable
`git_branch_track`. This global variable can be overwritten
by another repository when multiple Git repos run in the the same process.

Move this value into `struct repo_config_values` in the_repository to
retain current behaviours and move towards libifying Git.
Since the variable is no longer a global variable, it has been renamed to
`branch_track` in the struct `repo_config_values`.

Suggested-by: Phillip Wood <phillip.wood123@gmail.com>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Signed-off-by: Olamide Caleb Bello <belkid98@gmail.com>

To pave the way for reducing the global state tied to commit encoding
in a subsequent patch, functions like 'commit_tree()' and
'commit_tree_extended()' must be able to access a repository instance.

Plumb the 'struct repository' pointer down the call chain for these
APIs. For built-ins or subsystems already dependent on global state
(e.g., 'notes_cache_write()'), fallback to 'the_repository'.

No functional changes are introduced in this preparatory step.

Signed-off-by: Tian Yuchen <a3205153416@gmail.com>

To prepare for the elimination of the global state associated with
'log_output_encoding', functions responsible for formatting commit
messages, such as 'pretty_print_commit()' and 'pp_commit_easy()',
must be able to access a repository instance.

Plumb the 'struct repository' pointer down the call chain for these
APIs. Where no such context is readily available in built-ins or
high-level functions, fallback to 'the_repository'.

Signed-off-by: Tian Yuchen <a3205153416@gmail.com>

The global variables 'git_commit_encoding' and 'git_log_output_encoding'
prevent libification.

Migrate these variables into the 'struct repo_config_values'. This ensures
that they are safely accessed via the 'repo_config_values()' accessor which
prevents uninitialized or cross-repository access.

Note that these variables are not migrated to 'repo_settings'. As eagerly
parsed user preferences, deferring them to lazy evaluation would break
early validation.

Currently, during the config parsing phase in 'git_default_i18n_config()',
the values are still parsed into the 'the_repository' instance of
'repo_config_values', Since safely plumbing a repository pointer through
the 'git_default_config' callback machinery remains highly invasive due
to custom contexts being passed via the 'void *cb' parameter.
However, the read-paths (commit APIs and log formatters) updated in
previous patches are now fully plumbed to accept any repository
instance.

Signed-off-by: Tian Yuchen <a3205153416@gmail.com>