[Java] Fix typos and spelling

[asfimport]

Fix typos and spelling, mostly in docs and tests.

Reporter: Bryan Cutler / @BryanCutler
Assignee: Bryan Cutler / @BryanCutler

PRs and other links:

• GitHub Pull Request #5359

_{Note: This issue was originally created as ARROW-6534. Please see the migration documentation for further details.}

[asfimport]

Bryan Cutler / @BryanCutler:
Issue resolved by pull request 5359
#5359