Fleet UI: Add timestamps to host count on software detail pages

[RachelElysia]

Issue

For #24975

Description

• Add last updated at counts for the software details page, os details page, and vulnerabilities details page

Screenshot of all 3

Checklist for submitter

If some of the following don't apply, delete the relevant line.

• Changes file added for user-visible changes in changes/, orbit/changes/ or
• Manual QA for all new/changed functionality

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.82%. Comparing base (58afb10) to head (dc96ab0).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #25143      +/-   ##
==========================================
- Coverage   63.82%   63.82%   -0.01%     
==========================================
  Files        1615     1615              
  Lines      153602   153605       +3     
  Branches     4002     3950      -52     
==========================================
+ Hits        98043    98044       +1     
- Misses      47756    47759       +3     
+ Partials     7803     7802       -1     

Flag	Coverage Δ
frontend	53.26% <ø> (-0.01%)	⬇️

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[iansltx]

Code looks fine (though it feels like we could extract the host count tooltip message to a constant somewhere), but styling is a bit off. Which probably means tweaking the last-updated counts element.

From Figma:

Checked the font on that item in Figma and it's showing bold rather than standard, and I'm 99% sure the font-weight on the added items isn't bold. Additionally, seems like we're missing a tiny bit of left-pading on the count element to match up with Figma (and it feels like we do need that padding). Can't eyeball this exactly (I probably could if host count was 48) but maybe 4-8px?