Drop support of Node 16

[rschnekenbu]

According to https://nodejs.org/en/about/releases/,

• Node 16 is not maintained anymore.
• The next active release for Node (22) is planned for October this year

We should then drop the support from Node 16 in our builds (https://github.com/eclipse-theia/theia/blob/master/doc/runtime-policy.md).

Node 16 support blocked the update for jsdom for example (see #13943).

[jfaltermeier]

Just to add this this. A yarn upgrade will also pull in changes, that require node 18. See #13748
So for new users without an existing lock file, the current dependencies might already force them to use node 18.

[tsmaeder]

I believe we once formulated our policy once as supporting three releases: current, active and maintenance, so I we should be dropping support for 16, and soon 18 and start working on 24 instead.
That said, what are the consequences for adopters of Theia? If we believe that they consume mostly community releases, we would give them ~3 months to fix up their builds until 1.54 is released as a community release (1.52.0 being the current candidate). Sounds reasonable to me 🤷