[v14.x backport] fs: improve fsPromises readFile performance

[MoritzLoewenstein]

Improve the fsPromises readFile performance
by allocating only one buffer, when size is known,
increase the size of the readbuffer chunks,
and dont read more data if size bytes have been read.
Also moves constants to internal/fs/utils.

refs: #37583
(Old) Backport-PR-URL: #37703
PR-URL: #37608

This PR is backporting the fs readFile promise performance improvements to v14.x, essentially copying these two prs (i wasnt able to cherry-pick, not sure if its my git skills or something else):
#38061 "fs: move constants to internal/fs/utils.js"
#37703 "[v14.x backport] fs: improve fsPromises readFile performance"

[aduh95]

Assuming upstream and origin are configured in a classical way, you should be able to cherry-pick the original commits using the following commands:

git fetch upstream master git fetch upstream v14.x-staging git reset upstream/v14.x-staging --hard git cherry-pick 24fd791184ad0ba27f92ac49b820aec78e491296 git cherry-pick e216d8f4a1277e77903e9c2c716fefa3b196761b git cherry-pick b9fd4eb651dd26c3845aa46714593abae185455d git push origin HEAD:fs-read-promises-backport -f 

[MoritzLoewenstein]

Thank you :)

Added ArrayPrototypePush import to 2nd commit, your third cherry-pick is already in v14.

[targos]

Landed in f69c934...2b0e270. Thank you!