Deprecate OS_fsBlocksFree and OS_fsBytesFree

[jphickey]

Is your feature request related to a problem? Please describe.
As noted in #573 these functions return the value directly, which does double duty as an error code and therefore is limited to being int32 - but this type is not big enough for large file systems.

Describe the solution you'd like
Deprecate these functions in favor of OS_FileSysStatVolume() added in PR #717, which returns the information as a OS_statvfs_t object containing all relevant information.

Additional context
References to these functions within OSAL tests need to be fixed/replaced, as well as references in CFE/apps. This is a follow-on/completion of the fix for #573 / PR #717. Deprecation has to be done separately because the new function needs to exist before the refs can be changed.

Requester Info
Joseph Hickey, Vantage Systems. Inc.

[skliper]

@astrogeco @jphickey any way we can get a PR in this week? Delaying code review a week for this isn't very palatable, and I'd like to tag/branch and then remove all deprecated code ASAP.

[skliper]

@ejtimmon - one last (so far) impact to apps from OSAL, see cfs_fm/fsw/src/fm_cmds.c