Add back arrow to Terms of Service

[anandwana001]

Fixes #3051

1. moved to compose
2. added navigation check
3. added test

@shobhitagarwal1612 PTAL?

[codecov]

Codecov Report

Attention: Patch coverage is 62.74510% with 19 lines in your changes missing coverage. Please review.

Project coverage is 63.00%. Comparing base (c5ff10e) to head (ca7d410).

Files with missing lines	Patch %	Lines
...le/android/ground/ui/tos/TermsOfServiceFragment.kt	71.42%	3 Missing and 9 partials ⚠️
...va/com/google/android/ground/ui/compose/Toolbar.kt	20.00%	0 Missing and 4 partials ⚠️
...ain/java/com/google/android/ground/MainActivity.kt	25.00%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #3062   +/-   ##
=========================================
  Coverage     62.99%   63.00%           
- Complexity     1308     1309    +1     
=========================================
  Files           279      279           
  Lines          6780     6822   +42     
  Branches        954      966   +12     
=========================================
+ Hits           4271     4298   +27     
- Misses         1884     1888    +4     
- Partials        625      636   +11     

Files with missing lines	Coverage Δ
...ain/java/com/google/android/ground/MainActivity.kt	47.82% <25.00%> (-0.49%)	⬇️
...va/com/google/android/ground/ui/compose/Toolbar.kt	27.27% <20.00%> (-6.07%)	⬇️
...le/android/ground/ui/tos/TermsOfServiceFragment.kt	75.92% <71.42%> (-12.31%)	⬇️