Video: Allow MediaRecorder and WebRTC to select OS software encoder

Previously, if the OS supports H.264/H.265 SW encoding,
and doesn't support HW encoding, `GetSupportedProfiles()`
will still return a profile with `is_software_codec=true`
property, MediaRecorder doesn't filter this kind of profile
and potentially think there is HW GPU capability for this
codec, request encoding with `required_encoder_type` equals
to `prefer-hardware`, which cause `Videotoolbox` fail to
select the OS SW encoder.

Now, change the code to reuse the approach that currently
`VideoEncoder` is used. If there is OS SW encoding support
and not bundled a builtin SW encoder, change the option
`required_encoder_type` to `no-preference` and let VEA
able to use the OS SW encoder.

Bug: 40276507
Change-Id: Ic8a641eac50bc80ad0de29da1d1ae88bdb9273a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6002792
Commit-Queue: Sida Zhu <zhusida@bytedance.com>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1380130}