src: resolve miscellaneous conversion warnings (Windows)

[brodycj]

Checklist

• make -j8 test (UNIX [macOS]; Linux i386 & amd64) and vcbuild test nosign (.\vcbuild.bat nosign then .\vcbuild.bat test nosign nobuild as Administrator on Windows) PASS OK
• commit message follows commit guidelines

Additional item

• I hereby certify the statements in Developer's Certificate of Origin 1.1

Affected core subsystem(s)

src

Description of change

Resolve other conversion warnings not covered by #10141/#10142/#10143

This change along with #10140 (build options), #10141 (URL warning fixes), #10142 (crypto warning fixes), and #10143 (dtrace warning fix) resolves all warnings on Windows if vcbuild.bat is called with the following options: noperfctr without-inspector without-profiler

NOTE: This was originally a part of PR #10139 (build, warning, header, and include fixes).

ADDITIONAL NOTE: Some of the changes are marked // TBD POSSIBLE DATA LOSS: since I think we should examine these conversions at some point. I would be happy to take some or all of these out if necessary.

[jasnell]

/cc @bnoordhuis @addaleax

[brodycj]

I would like to submit these fixes in separate PRs for the following reasons:

• some rework needed in crypto: build warning fixes #10142 (crypto warning fixes) & dtrace: resolve conversion warning (Windows) #10143 (drace warning fixes) may also apply for the changes needed here
• I discovered that some fixes here such as url & crypto fixes should
  have been covered by url: build warning fixes #10141 & crypto: build warning fixes #10142
• This PR got the v8_inspector label. I think the V8 inspector fix should have been a separate PR for review.
• This PR got the dont-land-on-4x label. I don't think we want this to apply to all fixes proposed here.
• I suspect it will be easier to review and discuss the fixes in separate PRs.

In case anyone has already started to review (cc @jasnell @bnoordhuis @addaleax) the changes some quick feedback would be appreciated.