Move distutils import into Language.build_library

[narpfel]

Importing distutils takes more than 90% of the total import time of tree_sitter, but it is only used when compiling new languages. The common case should not need to pay for that.

Some measurements:

Without this PR:

$ python -Ximporttime -c 'import tree_sitter'
import time: self [us] | cumulative | imported package
[...]
import time:       613 |        613 |         json.encoder
import time:       347 |       2441 |       json
import time:      2406 |     129771 |     distutils
import time:       513 |     130284 |   distutils.ccompiler
import time:       444 |        444 |     shlex
import time:       176 |        176 |       distutils.py39compat
import time:       168 |        168 |       distutils._functools
import time:       927 |       1269 |     distutils.sysconfig
import time:       168 |        168 |     distutils._macos_compat
import time:       361 |       2240 |   distutils.unixccompiler
import time:       653 |        653 |   tree_sitter.binding
import time:       871 |     140812 | tree_sitter

With this PR:

$ python -Ximporttime -c "import tree_sitter" |& tail
import time:       214 |        214 |       _sha512
import time:       507 |       1625 |     random
import time:       309 |        309 |       _weakrefset
import time:       638 |        947 |     weakref
import time:       610 |       6328 |   tempfile
import time:       270 |        270 |     collections.abc
import time:       197 |        197 |     _typing
import time:      3145 |       3611 |   typing
import time:       404 |        404 |   tree_sitter.binding
import time:       702 |      16481 | tree_sitter