Allow both Python 2 and 3 to access StringIO

Update ESLint to 6.3.0

PR-URL: https://github.com/nodejs/node/pull/29382
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>

If there is no Python 2 available, use Python 3. This allows to test
running configure with Python 3.

PR-URL: https://github.com/nodejs/node/pull/29236
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

When looking for Python in the registry, as specified in PEP514,
this was not able to handle installations in a path with spaces,
like Program Files. This ensures the whole path is used, fixing the
issue.

PR-URL: https://github.com/nodejs/node/pull/29236
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/29371
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/29384
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/29302
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/29313
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Update ESLint to 6.2.2

PR-URL: https://github.com/nodejs/node/pull/29320
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>