DOCS: Add user guide section

[dipinknair]

• Move scripting , embedded instance, remote session inside user guide
• Added new section for CLIs (auto documentation of clis using sphinx-click)
• Added How tos

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.04% (target: -1.00%)	✅ ∅

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (e156b90)	2619	2253	86.03%
Head commit (e77053c)	2619 (+0)	2254 (+1)	86.06% (+0.04%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#1292)	0	0	∅ (not applicable)

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.06%. Comparing base (42fb444) to head (e77053c).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1292      +/-   ##
==========================================
- Coverage   86.13%   86.06%   -0.08%     
==========================================
  Files          40       40              
  Lines        2619     2619              
==========================================
- Hits         2256     2254       -2     
- Misses        363      365       +2     

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[github-actions]

The documentation for this pull request will be available at https://mechanical.docs.pyansys.com/pull/1292. Please allow some time for the documentation to be deployed.